The Research On The Coefficient Of Lateral Earth Pressure And It's Influence On The Internal Force Of Shield Segments

The first 20 years of the 21st century is the time in which the underground space will be greatly developed and utilized in China. As an low perturbed, environment protected, high-efficient, fast and safety method in urban tunnelling construction——Shield tunnelling construction, which will get an high-speed development and become as one of the major technologies applied in the urban tunnelling excavation, has a broad development prospect in our country. It is an important factor that influences the structure security and the construction economic, so it is of great significance to design the shield lining safely, economically and reasonably. Confirming the soil pressure on the lining reasonably is the key problem of the shield tunnel lining design. It is the basic demand to design the lining structure safely and economically. The horizontal soil pressure influences the vertical soil pressure and the sub-grade reaction's confirmation and it is difficult to calculate the horizontal soil pressure accurately. So it is very necessary and urgent to research and to take a analysis test to coefficient K0 of lateral earth pressure at rest which is this paper reflects the level of direct pressure on the physical and mechanical parameters of soil. We can get the following conclusion:1) The coefficient value of lateral earth pressure at test is 0.94 (estimating water and earth pressure together) and 0.92 (estimating water and earth pressure separately) by in-situ tests.2) For the permeability of silty clay soil was poor, the lateral pressure of the soil was a little bigger at the initial loading for the test and the initial coefficient of lateral pressure was bigger too. The silty sandy soil is the good permeability, the lateral pressure coefficient changes slightly over time. In the depth of soil, the coefficient of lateral pressure (for estimating water and earth pressure separately, mainly for the silty sandy soil) was between 0.25 and 0.57 after consolidation, and the initial lateral pressure coefficient of the silty clay soil (for estimating water and earth pressure together) was between 0.72 and 1.0.3) The impact of the coefficient of lateral earth pressure at rest of the estimating water and earth pressure together was higher than the lateral pressure at rest of estimating water and earth pressure separately. Both the absolute value of maximum sagging moment and maximum hogging moment of internal force of shield segment and the coefficient of lateral earth pressure at rest decreased linearly during internal force analysis of shield segments. Finally, we should consider the external load calculation method carefully to select coefficient of lateral earth pressure at rest.