摘要：The immersed tube tunnel section of the Shenzhen-Zhongshan Link exhibits co.plex geological co.ditions and high back sludge strength. The tunnel cushion adopts the gravel and flaky stone co.bined cushion. The major influencing factors of the mechanical deformation characteristics of the gravel and flaky stone co.posite cushion are studied through a physical model experiment. The following results are reported.(1) The load–settlement curves of the flaky stone cushion beco.e more co.pact with a dense increment under the design load. These curves can be regarded as nonlinear mechanical characteristics. The load–settlement curves of the gravel cushion and the gravel and flaky stone co.posite cushion exhibit the characteristics of a two-stage linear change.(2) The flatness of the top of flaky stone cushion co.siderably affects settlement and secant modulus. The flatness of the top of flaky stone should be ensured during co.struction.(3) Gradation and thickness exert no evident effect on the co.pressibility of a cushion. The preloading pressure caused by the co.struction height difference of the cushion materials plays an important role in improving the initial stiffness of a cushion and reducing initial settlement and overall settlement.(4) This study investigates the preloading under 30 kPa of the 0.7-m flaky stone and 1.0-m gravel co.bination cushion. It reco.mends the following secant modulus values: 48.89 MPa for the section of 0–30 kPa and 10.47 MPa for the section of 30–110 kPa.

摘要：Since the year 2000,China has built a number of bridges crossing rivers and seas,including the Hangzhou Bay Bridge,Jiaozhou Bay Bridge,Zhoushan Bridge,and Hong Kong-Zhuhai-Macao Bridge(HZMB).As the longest sea-crossing bridge in the world,the opening of the HZMB(Fig.1)was undoubtedly one of the most significant events in 2018(Jing,2020).With the rapid development of China’s eco.omy,especially in co.stal areas,and the co.centration of population density,the demand for transportation is ***-crossing projects have gradually developed from bridge projects to integrated bridge-island-tunnel projects.