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采用物理试验方法,初步开展饱和砂与井壁混凝土界面竖向剪切试验,获得了界面竖向抗剪强度指标;基于数值计算,进一步研究厚风积砂覆盖地层立井井壁竖直附加力的变化规律。结果表明:风积砂地层中,井壁竖直附加力随深度的增加呈现出非线性增长规律,并在风积砂含水层与基岩交界面附近达到极值;进入基岩段后,竖直附加力部分由基岩分担,附加力急剧减小。在厚度超过100 m的风积砂地层中,随着含水层水位的不断下降(如超过20 m),传统的双层复合井壁结构在竖直附加力等作用下,于基岩交界面附近可能出现井壁破裂灾害,应采用适应地层沉降的可缩井壁结构限制竖直附加力的增长。
The physical test method was used to carry out the vertical shear test on the interface of saturated sand and lining concrete, and the vertical shear strength index of the interface was obtained. Based on the numerical calculation, the vertical additional force The law of change. The results show that in the aeolian sand stratum, the vertical additional force of the borehole wall shows a nonlinear growth law with the increase of the depth and reaches the extreme near the interface between the aeolian sand aquifer and the bedrock. After entering the bedrock section, the vertical Straight additional part of the burden by the bedrock, additional force decreased dramatically. In the aeolian sands with thicknesses exceeding 100 m, with the ever-decreasing water level of the aquifer (for example, more than 20 m), the traditional double-layer composite wall structure is under the action of vertical additional force and is near the interface of the bedrock Shaft wall rupture disasters may occur. The shrinkage wall structure adapted to formation subsidence should be used to limit the vertical additional force.