Tương quan giữa súc chống cắt không thoát nước(Su) với kết quả thí nghiệm xuyên tĩnh của sét mềm bão hòa nước - trường hợp đất cải tạo khu nhà bè, cảng Thị Vãi, Việt Nam

Abstract

The undrained shear strength (S_u) of clay is generally obtained from laboratory tests on undisturbed soil or direct measure using field vane shear test. As cone penetration test (CPT) has become a popular method for exploring the subsoil stratification, it will be useful for pratising engineers to evaluate the S_u of clay based on CPT results if the correlation between the S_u and the cone resistance (q_c) is established. In this paper, the data of S_u from the field vane shear tests and cone resistance (q_c) from the sites located on typical saturated soft soil in several regions in Ho Chi Minh City where they are collected and used for establishing an empirical correlation. An empirical cone factor (N_k) in the range of  numbers is obtained. This N_k value can be used to evaluate the S_u of clays. This obtained N_k values are compared with N_k values of other known soft clays. Generally, the undrained shear strength of the saturated soft clay increases with depth. An emperical correlation of S_u with effective overburden pressure is developed and the cone bearing factor (N_k) will be computated based on local experience. The cone factor (N_k) of 17 ± 8 is recommended using S_u= q_c−ơ_v0 /N_k and of 28 ± 8 using S_u = q_c/N_c . The results show that the N_k values is in the agreement with the published correlations. It is concluded the correlation factors obtained in this study can be used for saturated soft clay in the study regions and can be applied for computation to evaluate the pile capacity.