Professional:Professor
Department:Geological Engineering Teaching and Research Office
Email:xiewanli@nwu.edu.cn
1、 Personal profile
Xie Wanli, female, doctor of engineering, Professor, doctoral supervisor, non party personage, director of geological engineering teaching and Research Office, director of loess dynamic disaster and ecological environment restoration technology research center of Northwest University.
He has successively presided over and completed 1 National Natural Science Fund project, 1 National Natural Science Youth Fund project, 1 national key research and development project subproject, 1 major scientific and technological problem solving project subproject, 1 provincial international key cooperation project, 1 provincial international cooperation project, 1 Shaanxi Natural Science Youth Fund, 1 special fund of Shaanxi Provincial Department of education, and China Mobile The State Key Laboratory of mechanics has two independent research projects, two ministerial key laboratory projects, two large-scale land and resources investigation projects and six horizontal projects. It has participated in more than 40 projects, four National Natural Science Foundation projects and four major projects of the Ministry of railways. Presided over 9 national, provincial and university level teaching projects, 1 construction project of provincial excellent resource sharing course rock mechanics, and 1 construction project of the first SPOC course rock mechanics of Northwest University. He has published more than 40 papers, one monograph, 9 authorized patents and 9 software copyrights as the first author. In the filling test of Daxi passenger dedicated line, it is proposed that 6% cement can eliminate the collapsing and seismic subsidence of loess; the strength of reinforced loess has a certain relationship with the location and interval of reinforcement, and the reinforcement in the middle of the soil is a more economical and reasonable way of reinforcement. In 2007, he won the Excellent Doctoral Thesis Award of Shaanxi Province; in 2017, he won the first prize of Shaanxi University Science and Technology Award (3 / 10); in 2017, he won the first prize of Shaanxi Province Science and Technology Progress Award (3 / 10).
1. Education experience
In July 1997, he graduated from the Department of hydrogeology and engineering geology of Xi'an University of Engineering (Chang'an University) and obtained a bachelor's degree in hydrogeology and engineering geology;
In August 2001, he obtained a master's degree in water conservancy and Hydropower Engineering from the school of electric power engineering, Kunming University of science and technology;
In July 2004, he obtained a doctor's degree in geological engineering from the Department of geology, Northwest University;
2. Scientific research and academic work experience
2012 / 1 - 2013 / 82015 / 7 - 2015 / 9, visited the Department of civil engineering at the University of Colorado Boulder twice successively;
Since September 2004, he has been a teacher in the Department of geology of Northwest University;
In 2007, he was promoted to associate professor, and in the same year, he was selected as supervisor of master degree in geological engineering;
In 2017, he was selected as the doctoral supervisor of geological engineering;
Promoted to Professor in 2019.
3. Social part-time job
Member of international geosynthetics Association
Member of International Association of engineering geology and environment (IAEG)
Member of the reinforcement Committee of China geosynthetics Engineering Association
Member of Education Committee of China geosynthetics Engineering Association
Member of engineering geology Committee of Chinese Geological Society
Director of rock mechanics and Engineering Society of Shaanxi Province
Expert of geological disaster prevention and control in Shaanxi Province
Experts of mine geological environment management and land reclamation in Shaanxi Province
Xi'an Geological Disaster Prevention and control expert
Yulin natural resources expert
2、 Teaching situation
1. Undertaking courses
Lecture: three undergraduate courses of rock mechanics, basic engineering and numerical simulation of Geological Engineering
Two courses of numerical simulation of geological engineering and advanced soil mechanics for Postgraduates
Field practice of geotechnical engineering investigation for Undergraduates
2. Undertake education reform projects
(1) Comparison and Enlightenment of graduate training methods between China and the United States, research project of graduate education and teaching reform of Northwest University, principal, 2013-2014
(2) Development of geological engineering in situ test simulation experiment system, experimental teaching project design fund project of Northwest University, person in charge, 2015-2016
(3) Rock mechanics, 2015 provincial excellent resource sharing course construction project of Shaanxi University, person in charge, 2015-2017
(4) Rock mechanics, the first SPOC construction project of Northwest University in 2016, person in charge, 2016 / 2-2016 / 12
(5) Construction of geological engineering numerical simulation laboratory, renewal and supplement project of Northwest University Teaching Laboratory, person in charge, 2016
(6) Geological engineering laboratory construction, Northwest University Teaching Laboratory update and supplement project, person in charge, 2016
(7) Research on "543" virtual simulation experiment teaching system of geological engineering based on the training of excellent engineers (17bg010), 2017 key research project of Shaanxi higher education teaching reform, person in charge, 2017 / 7-2019 / 6
(8) Virtual simulation system for geological engineering in situ test, 2018 virtual simulation test teaching project of Shaanxi Province, person in charge, 2018
(9) Geological engineering in situ test virtual simulation system, 2018 national virtual simulation test teaching project, person in charge, 2019
3. Guide students
There are 25 innovative experimental projects for guiding college students and postgraduates, including 2 national, 3 provincial, 6 school level, 9 National Base college students' innovative funds, and 5 school level Postgraduates' innovative funds.
42 undergraduates and 22 postgraduates were supervised.
4. Teaching Awards
(1) In 2008, he won the third prize of the teaching competition of young teachers in the Department of geology of Northwest University.
(2) In 2009, the Innovation Fund for college students under the guidance of the national geoscience class won the second prize.
(3) In 2011, he was awarded the excellent instructor of the national innovative experiment program for college students.
(4) In 2011, he won the title of excellent teacher of Northwest University.
(5) In 2011, the Innovation Fund for college students under the guidance of the national geoscience special prize.
(6) In 2011, the college students won the third prize of reinforced earth retaining wall design of national college students.
(8) 2017 advanced individual title of Northwest University.
(9) In 2017, he won the title of excellent teacher of Northwest University.
(10) In 2016, guide graduate students to participate in 2016 Shaanxi Youth public welfare competition Bronze Award.
(11) In 2017, he directed postgraduates to participate in the gold medal of 2017 Shaanxi Youth public welfare competition.
(12) Excellent master's thesis instructor of Northwest University in 2018.
(13) In 2018, he won the title of excellent teacher of Northwest University.
(14) In 2018, he won the title of teaching expert of Northwest University.
3、 Scientific research
1. Scientific research projects
(1) Project of science research foundation of Northwest University, 04nw59, experimental study on constitutive relationship of reinforced soil, 2005 / 01-2006 / 12, principal
(2) Youth fund of NSFC, 40502028, research on strength and deformation characteristics of reinforced loess, 2006 / 1-2008 / 12, principal
(3) Strength and deformation test and finite element analysis of reinforced loess, youth fund of Shaanxi Natural Science Foundation, 2007-2008, principal
(4) Special experimental research of Da Xi passenger dedicated line, 2010g005-c-1, second level subject of major scientific research project of the Ministry of railways, 2009, principal
(5) Special fund of Provincial Department of education, 09jk780, study on formation mechanism of loess landslide in Nanyuan, Jingyang, 2010 / 01-2012 / 12, person in charge
(6) Independent research project of State Key Laboratory of continental dynamics, bj091352, seismic technology of reinforced loess in subgrade treatment of high-speed railway, 2010-2011, principal
(7) Open fund of Key Laboratory of Western Ministry of mineral resources and geological engineering, chd2010jc142, dynamic triaxial test research on reinforced loess, 2011-2012, principal
(8) Subproject of Shaanxi major scientific and technological problem solving project, 2011ktzb03-02-03, coordinated development of urban engineering construction and environment, 2013 / 01-2015 / 12, principal
(9) Research on Collapsibility characteristics of loess under high pressure, Shanxi science and technology research project, person in charge, 2010-2011
(10) Independent research project of National Key Laboratory, bj14268, research on starting mechanism of loess mud flow and development of alarm device in Yan'an area, June 2014-june 2016, person in charge
(11) Analysis and Research on quaternary structural evolution process of Ankang basin, person in charge, 2011
(12) Analysis and Research on quaternary structural evolution process of Shangluo basin, person in charge, 2010
(13) Open fund of Key Laboratory of loess geological disaster, Ministry of land and resources, klglamlr201502, research on Collapsibility characteristics of loess under high pressure in Xi'an area, 2015 / 9-2016 / 12, principal
(14) Shaanxi international science and technology cooperation and exchange program,
2016kw-030, research on engineering geological problems caused by dynamic and static loads in Yan'an mountain shifting and ditch filling project, 2016 / 1-2017 / 12, person in charge
(15) National key research and development project, 2017yfd080501, research and development of engineering geology and soil collapsible stability technology and standard for ditch and land making, 2017 / 7-2020 / 12, person in charge
(16) Research on groundwater pollution and health early warning in Northern Shaanxi, person in charge, 2017
(17) Yulin groundwater pollution and health and economic research, person in charge, 2017
(18) Project of China Geological Survey Bureau, ht20170487, comprehensive geological survey of the section within the Silk Road, comprehensive geological survey of Guanzhong Tianshui Economic Zone (comprehensive geological survey of the old revolutionary base area of Yan'an) - General Survey subproject of diseases in the old revolutionary site of Yan'an, 2017 / 1-2017 / 12, person in charge
(19) Technical research and development of slope prevention scheme for typical sections along the Yellow River (Heyang section) in Shaanxi Province, contract project, person in charge, 2018
(20) Project supported by National Natural Science Foundation of China, 41772323, study on mechanism and evolution mode of geological disaster induced by high-pressure, immersion and dynamic compaction of loess high fill, 2018 / 1-2021 / 12, principal
(21) project of China Geological Survey Bureau, [2018] 01-33, comprehensive geological survey of Guanzhong Tianshui Economic Zone within the Silk Road (comprehensive geological survey of the old revolutionary base area of Yan'an dd20189270) - Comprehensive Geological Survey and division of natural resources in Yanchang County, may 2018 December 2018, person in charge
(22) project of China Geological Survey Bureau, comprehensive geological survey of Guanzhong Tianshui Economic Zone (comprehensive geological survey of the old revolutionary base area of Yan'an) - 1:10000 geological disaster survey and risk assessment of Zhidan County and important towns, 2019 / 5-2019 / 12, person in charge
(23) Tongchuan geological disaster monitoring and early warning management platform construction project, March 2019 August 2019, person in charge
(24) key projects of Shaanxi international science and technology cooperation and exchange program,
2019kwz-02, research on engineering geological problems caused by dynamic and static loads in Yan'an mountain moving and ditch filling project, 2019 / 1-2020 / 12, person in charge
2. Academic papers
[1] Xie Wanli, Zhang Linhong. Foundation treatment method and its application in engineering practice. Journal of Kunming University of science and technology, 2000, (6): 78-80
[2] Xie Wanli, Wang Jiading, Zhang Linhong. Experimental study on strength and deformation characteristics of earth rock coarse aggregate. Journal of rock mechanics and engineering, 2005 (3): 430-437. (included in EI)
[3] Zhang Linhong, Xie Wanli, Liu Rongpei. Stress strain characteristics of rockfill under the condition of equal stress ratio path. Dam observation and geotechnical test, 2001, (3): 56-61
[4] Wang Jiading, Xie Wanli, study on prediction method of large ground displacement caused by earthquake liquefaction, Journal of engineering geology, 10 (added): 138-1402002
[5] Wang Jiading, Xie Wanli, Luo Fengtao, finite element calculation of deformation of high fill reinforced earth dam in Huoxian County, Shanxi Province, JOURNAL OF NORTHWEST UNIVERSITY (Network Edition), inaugural No. 1 (1): 2003
[6] Zhang Linhong, Xie Wanli, Liu Rongpei. Study on elastic-plastic constitutive model of earth rock coarse aggregate. Geotechnical engineering technology, 2002,
(2):95-99
[7] Wang Jiading, Xie Wanli, prediction method of large ground displacement caused by earthquake liquefaction in loess area, see: Collected Papers of Professor Xiao Shufang on his 70th birthday, 139-145, Changchun: Jilin Science and Technology Press, 2004, (increase): 138-141
[8] Xie Wanli, Wang Jiading, et al. Application of fuzzy information optimization method in loess collapsibility evaluation. Journal of Northwest University, 2005 (1): 69-73
[9] Xie Wanli, Wang Jiading, et al. Triaxial experimental study on deformation and strength characteristics of reinforced loess, progress in Geoscience, 2004,19 (increase): 333-339,
[10] Zhang Xinjun; Wang Jiading; Gu Tianfeng; Xie Wanli, study on landslide mechanism of toll station of liechai highway in Tongchuan, JOURNAL OF NORTHWEST UNIVERSITY (NATURAL SCIENCE EDITION), 2005, (3): 335-338
[11]Wanli
XIE, Jiading WANG, Jinhu YUAN, Rui’e Li. Application in Evaluation of Loess
Collapsibility with Information Diffusion Technique. Applied Computational Intelligence.
World Scientific: Blankenberge, Belgium, sep.2004:350-357 (included in EI)
[12] Xie Wanli, Wang Jiading. Application of information diffusion technology in stability evaluation of reinforced high fill embankment. Journal of applied foundation and Engineering Science, 2004 (Supplement) 193-198 (included in EI)
[13] Xie Wanli, Wang Jiading. Information diffusion model in the stability evaluation of reinforced high embankment. Journal of natural disasters, 2006,15, (1): 99-102
[14] Wang Jiading, Xie Wanli, Luo Fengtao. Finite element analysis of the stability of high fill reinforced loess embankment. Geographic science
2007,26(3):56-59.
[15] Xie Wanli, Xue Jiangong, Chang Bo. Triaxial experimental study on the dynamic characteristics of reinforced soil, disaster science (Supplement) 2008, (9): 74-79
[16] Qin Fengyan; GE Haiyu; Xie Wanli, theoretical analysis of negative friction calculation of pile foundation in collapsible loess area considering time effect, Journal of West Anhui University, 2012, (2): 110-113
[17] Peng Shujun, Xie Wanli *, Ma Yan, Wang Jiading. Effect of water content on the strength of loess with different reinforcement methods [J]. Bulletin of soil and water conservation, 2013, (4): 275-278
[18] Liu Rui, Wang Jiading, Xie Wanli, Wen duwu. Characteristics analysis of debris flow disaster in Yan'an area [J]. Groundwater, 2013, (2): 130-131 + 138
[19] Wang Jiading, Peng Shujun, Ma Yan, Xie Wanli. Dynamic test of Cement Improved Loess under vibration load of high-speed train [J]. Journal of earthquake engineering, 2013, (1): 35-41
[20] Chen Guo, Xie Wanli, Liu Qiang. The microstructural characteristics and environmental significance of late Pleistocene loess in Shangzhou [J]. Journal of Gansu science, 2012, (4): 4-7
[21] Liu Qiang, Xie Wanli, Wen duwu. Study on strength change of loess slope after excavation [J]. Groundwater, 2012, (3): 208-210
[22] Wen duwu, Xie Wanli, Liu Qiang, Wang Qingman. Analysis of excavation unloading stability of loess high slope based on ANSYS [J]. Groundwater, 2012, (3): 189-191
[23] he Xiaoliang, Xie Wanli, Ding Yong. Triaxial test and Research on shear strength of loess in the South plateau of Jingyang [a]. Proceedings of China Geological Society Engineering Geology Professional Committee. 2010 National Engineering Geology annual meeting and "engineering geology and Haixi construction" academic conference [C]. China Geological Society engineering geology Professional Committee: 2010, (6): 76-87
[24] Jiang Zhenwei, Xie Wanli. Analysis and Countermeasures of ground cracking in an oil transportation station in Northern Shaanxi [J]. JOURNAL OF NORTHWEST UNIVERSITY (NATURAL SCIENCE EDITION), 2010, (6): 1064-1068
[25]Yan
Ma, Wanli Xie, Shujun Peng. Study on reinforced scheme of reinforced loess by triaxial tests.
Second International Conference on Mechanic Automation & Control
Engineering, 2011:6147-6151 (included in EI)
[26] Wang Jiading, Peng Shujun, Ma Yan, Xie Wanli, dynamic test of Cement Improved Loess under vibration load of high-speed train, Journal of earthquake engineering, 35 (1): 35-412013
[27]Peng
Shujun,Ma Yan,Wang Jiading,Xie Wanli.Application of fuzzy information
optimization technology on analysis of loess landslide stability[J]. Applied
Mechanics and materials. 2013, vol.324, PP: 2389-2395 (included in EI)
[28] Wang Yanshou; Xie Wanli; GE Ruihua; Wu Guanghui; Wang Xiaofeng; Wang Huajiang, application of TSP advanced prediction method in Qin'an high risk tunnel, science and technology and engineering, 2014, (34): 97-103
[29] Xie Wanli, Wang Yanshou, Ma Zhonghao, Ge Ruihua, Wang Jiading, research status and development trend of loess collapse mechanism [J], modern geology, 2015, 29 (2): 397-407
[30] Gai Hailong; Xie Wanli; Xu Yuanjun, evaluation on the vulnerability of landslide and collapse in Chang'an District Based on fuzzy evaluation method [J], Anhui Agricultural Science, 2015, (17). 155-156. Published first.
[31] Gai Hailong, Wang Jiading, Wang Jianbin, Xie Wanli. Stability analysis of railway slope in Loess Area Based on fuzzy evaluation method [J]. Bulletin of soil and water conservation, 2015,35 (3): 157-161
[32] Ge Ruihua, Xie Wanli, Feng Li. Experimental study on the moisture absorption characteristics of Q3 loess in Jingyang South tableland [J], northwest geology, 2015 (48), 4:218-224
[33] Teng Hongquan, Xie Wanli *, Gai Hailong, Ge Ruihua, Guo Qianyi. The application of fractal dimension theory in the development and spatial distribution of geological disasters -- Taking the landslide and collapse geological disasters in Chang'an District as an example [J], geological disasters and environmental protection, 2016 (27), 44-50
[34] Xie Wanli, Ge Ruihua, Guo Qianyi, Wang genlong, Cheng Tiane. Study on the macroscopic mechanical response and microstructure of loess under irrigation [J]
Hydrogeology engineering geology, 2017,44 (2): 82-89
[35] Guo Qianyi, Xie Wanli, Zhao Dong'an. Analysis of deformation characteristics of loess landslide [J]. Urban geography, 2017 (11x): 96-96
[36] Li Dongming, Xie Wanli. Analysis of landslide induced by excavation slope in Xi'an area - Baqiao area slope as an example [J]. Urban geography, 2017 (3x): 66-67
[37] Ma Yan, Xie Wanli, Peng Shujun, Wang Jiading. Triaxial experimental study on the influence of reinforcement methods on the dynamic characteristics of loess. Hydrogeological engineering geology [J], 2017,44 (4): 50-56
[38] Xie Wanli, Teng Hongquan, Du Lei, et al. Classification and characteristic analysis of landslides in Xi'an area [J]. Journal of earth environment, September 1, 2018: 79-88
[39]Wan-Li
Xie, Ping Li*, ect. Prediction of the wetting-induced collapse behaviour using
the soil-water characteristic curve[J],Journal
of Asian Earth Sciences,2018(151),259-268.
(included in SCI)
[40] Hu Sheng, Qiu Haijun, Wang Xingang, Xie Wanli, long Yongqing, etc. extraction of characteristic parameters of loess landslide based on high-resolution terrain and its application significance [J]. Quaternary research, 2018,38 (2): 367-379
[41] XIE
Wan-Li, LI Ping*, Zhang Mao-sheng ect. Collapse behavior and microstructural
evolution of loess soils from the Loess Plateau of China[ J],Journal
Of mountain science, 2018, 15 (8)
[42] Xie Wanli, Teng Hongquan *, Du Lei, etc. Application of GIS combined with fuzzy information method in disaster risk zoning -- Taking the landslide geological disaster in Xi'an as an example [J]. Disaster science, 2018,33 (03): 111-116
[43] Liu Yingying, Xie Wanli *, Zhu Hua, et al. Study on Loess consolidation collapsibility test and prediction model in Jingyang area, Shaanxi [J]. Northwest geology, 2018,51 (02):
227-233.
[44] Du Lei, Xie Wanli. Research progress and Prospect of bearing capacity of urban geological environment [J]. Journal of Institute of disaster prevention technology, 2018,20 (02): 15-20
[45] LI Ping,
XIE Wan-Li*, ect.. Microstructural evolution of loess soils from the Loess
Plateau of China [J], catena, 2019173 (2) 276-288. (included in SCI)
3. Monograph
Xie Wanli, Wang Jiading, stability analysis of reinforced loess, Shaanxi science and Technology Press, 220K words, 2006, 12
4. National patent
Invention patent:
(1) Gu Tianfeng, Wang Jiading, Xie Wanli, a sample cutter for preparing undisturbed loess for triaxial test, zl201110024140.92012, China
(2) Wang Jiading, Ma Yan, Peng Shujun, Li Jiadong, Xie Wanli, Gu Tianfeng, monitoring system of soil internal stress change under the condition of water immersion in Loess field, zl201310087230.12014, China
(3) Xie Wanli, Wang Jiading, Ge Ruihua, Wen duwu, Gu Tianfeng, a cement improved reinforced loess subgrade for high-speed railway and its construction method, zl201410848981.52016, China
(4) Xie Wanli, Li Dongming, Qu Rui, Ge Ruihua, Yu Hong, Guo Qianyi, Liu Yingying, a loess mudflow alarm starting device, ZL 201510520053.02018, China
(5) Xie Wanli, Guo Qianyi, Wei Baomin, Du Lei, Wang Xingang, a honeycomb geocell retaining wall with ecological restoration function and its construction method, zl201610935810.52018, China
(6) Xie Wanli, Guo Qianyi, Liu Yingying, Du Lei, Wang Yong, a typical loess collapse control technology based on ecological restoration, zl201610619719.22018, China
Utility model:
(1) Xie Wanli, Wang Jiading, Li Dongming, Ge Ruihua, Yu Hong, Guo Qianyi, a loess mudflow alarm starting device, zl201520633854.32015, China
(2) Guo Qianyi, Xie Wanli, a honeycomb geocell retaining wall with ecological restoration function, ZL 201621159504.92016, China
(3) Wang Jiading, Ma Yan, Peng Shujun, Li Jiadong, Xie Wanli, Gu Tianfeng, monitoring system of soil internal stress change under the condition of water immersion in Loess field, zl201320124525.72013, China
5. Software copyright
[1] Xie Wanli, Liu Yingying, Liang Yingying, Zhao Dong'an, Li Deyi, on-site direct shear virtual simulation software, vssdp 1.02018sr007986, China, January 2018
[2] Xie Wanli, Yang Hui, Liu Tao, Wang Yong, Liu Yingying, dynamic penetration virtual simulation software, vssdp 1.02018sr007324, China, January 2018
[3] Xie Wanli, Liu Tao, Yang Hui, Dan Shuai, Liu Yingying, virtual simulation software for rock stress test, vssrmst 1.02018sr005381, January 2018
[4] Xie Wanli, Yang Hui, Liu Tao, Wang Yong, Liu Yingying, static load test virtual simulation software, vssslt 1.02018sr005339, January 2018
[5] Xie Wanli, Liang Yingying, Du Lei, Wang Yong, Zhao Dong'an, early warning system of geological disaster in Qinba Mountain Area Based on field monitoring, gdwsbfm v1.02018sr198592, August 2017
[6] Xie Wanli, Kang Lei, Yang Hui, Du Lei, hydraulic fracturing virtual simulation software, vsshf v1.02019sr0050237, November 2018
[7] Xie Wanli, Chen Danling, Chang Yilun, Kang Lei, Jack load virtual simulation software, vssljlt v1.02019sr0050251, November 2018
[8] Xie Wanli, Chen Danling, Chang Yilun, Kang Lei, pile foundation static load virtual simulation software, vsspflt v1.02019sr0050234, November 2018
[9] Xie Wanli, Liu Tao, Wang Jianhao, Chen Danling, virtual simulation software for rock acoustic testing, vssrwt v1.02019sr0050261, November 2018
6. Scientific research awards
(1) In 2007, he won the Excellent Doctoral Thesis Award of Shaanxi Province.
(2) Wang Jiading, Wang Yu, Xie Wanli, Gu Tianfeng, Zhang Xinjun, Yuan Jinhui, urban engineering geological Atlas of Xianyang, won the first prize of national urban survey excellent project in 2005 and the second prize of provincial excellent project survey in Shaanxi Province in 2003.
(3) In 2017, it won the first prize of Shaanxi University Science and technology award, research on Key Technologies of major engineering geology and disaster prevention and control in railway construction in loess area, and scientific and technological progress of Shaanxi Provincial Department of Education (3 / 10).
(4) 2017 Shaanxi science and technology progress first prize, loess disaster mechanism, prevention and control key technology and its application in major railway projects, Shaanxi science and Technology Department (3 / 10).
Recruit master's degree, doctor's degree and postdoctoral degree in geological engineering, geotechnical engineering, environmental engineering, geographic information system and big data analysis. Welcome you to join in the cooperative research!
Email: xiewanli@nwu.edu.cn ; 22560953@qq.com