论文部分内容阅读
推导了新建地铁上穿施工引起的既有隧道结构的卸荷附加应力系数解析解,利用Maple软件对卸荷面积、卸荷中心距既有隧道水平距离、卸荷平面至既有隧道顶部距离、卸荷宽长比等关键卸荷参数与附加应力系数的关系进行研究,旨从弹性卸荷理论的角度提出了地铁上穿工程中如何减小既有隧道结构卸荷效应的措施。研究表明:随着卸荷面积的增大,底板下方不同深度处的附加应力系数逐渐增大,应尽量减少一次卸荷面积,减少开挖进尺;当既有隧道处于卸荷面积边界附近时,卸荷附加应力系数急速衰减,应对开挖卸荷长度范围内的既有线结构周围土体进行重点加固;附加应力系数随着夹层土厚度的增加逐渐减小,应尽量加大新旧结构之间的距离;随着宽长比的增大,卸荷中心下的附加应力系数逐渐减小,建议采用长条形的土体开挖方式;在相同的卸荷面积条件下,泊松比对附加应力系数的影响较小。
The analytic solution of additional stress coefficient for unloading of existing tunnel structure caused by construction of newly built subway is deduced. By using Maple software, the unloading area, the distance from unloading center to the existing tunnel, the distance from unloading plane to the top of existing tunnel, Unloading width-to-length ratio and other key unloading parameters and additional stress coefficient of the relationship between the study, from the perspective of the theory of elastic unloading put forward on the subway through the project to reduce the existing tunnel structure unloading effect measures. The results show that with the increase of the unloading area, the additional stress coefficient at different depths under the floor gradually increases, the unloading area should be reduced as much as possible to reduce the excavation footage. When the existing tunnel is near the unloading area boundary, Unloading additional stress coefficient rapid decay, excavation should be within the scope of the length of unloading existing soil reinforcement around the existing structure of key reinforcement; additional stress coefficient with the thickness of the interlayer soil gradually decreased, we should try to increase the old structure Distance; as the aspect ratio increases, the additional stress coefficient under the unloading center gradually decreases. It is recommended to use the strip-shaped excavation method; under the same unloading area conditions, the Poisson’s ratio to the additional stress The effect of the coefficient is small.