天府新机场多层地下空间建设对地下水渗流场的影响

发布时间：2018-05-07 11:27

本文选题：地下水渗流场 + 地下空间修建　；参考：《成都理工大学》2017年硕士论文

【摘要】：天府新机场地下空间开挖具有其空间结构上与地质条件上的独特性。地下空间多层且为交叉性交通走廊:第一层为埋深-8m的综合交通枢纽,第二层地铁车站顶板高程-9.42m,底板高程-11.1m,第三层为地铁与高铁车站,埋深-23.3m。地下空间开挖深且布局交错加大了地下空间建设难度。天府新机场地处龙泉山以东,沱江以西,场区内丘陵遍布,水塘密集,地表水十分丰富。由于新机场位于简阳鼻状背斜之西北翼,地层展布为产状平缓的单斜砂泥岩互层状地层,虽红层区赋水条件相对较差,但场区内揭露的局部弱承压水使场区内水文地质条件变得复杂。结合以上特点,天府新机场地下空间开挖对渗流场的影响较为复杂,每一步工况的细微差别都影响着渗流场的波动。本文根据对研究区内地质条件、水文地质条件、地下工程概况等资料,利用ModFlow模拟了地下水渗流场在不同工况下的变化,并大胆假设,减少不必要的施工步骤,观察是否会影响周边地下水环境的巨变,以此为施工方案提出合理的优化措施。根据一系列的模拟结果得到以下结论:(1)场平后莲花水库小支流被填埋,填埋后由地下水排泄区演变为地下水的补给—径流区,地下水与莲花水库、金鸡河与举人河的补排关系不变,但补给径流强度减弱。由于场平强烈改变了场地内地形地貌,使地下水分水岭消失,地下水局部壅高,壅高值0.04m。(2)场平后应先将基坑内水位降至基坑底部以下0.5m后再开挖,模拟结果表明,基坑降水影响半径与滤管长度呈正比,三层基坑降水影响半径约270~650m,距离地表水系较远,可不设置止水帷幕。(3)基坑降水将导致地下水渗流场形态扭转,并为地下水提供了新的排泄途径,地下构筑物对地下水的阻拦作用被削弱。单斜状砂泥岩互层结构导致部分地下水顺层流动,第一层与第二层基坑降水会加快地下结构迎水面的径流速度。(4)由于第三层地铁与高铁车站的修建仅减小了原过水断面的7%,且与地下水流向呈大角度相交,该层车站的修建对地下水的拦截作用稍弱,地下水渗流场呈地下结构迎水面水位较高,背水面水位较低的形态,但未出现地下水壅高现象。(5)第二层地铁车站位于砂岩层,过水断面减少了19.87%,且车站长轴方向与地下水顺层流呈90°交角,因此与第三层车站相比,该层对地下水的阻拦作用略有提高。当第二层车站与第三层车站同时存在,地下构筑物迎水面地下水位高于背水面,二者共同拦截了来自研究区北部的径流,高水位区域渗流场形态与地下构筑物轮廓一致。(6)与第三层基坑回填相比,第二层基坑上部回填对地下水渗流场的恢复更有利。基坑回填后,第二层车站迎水面地下水位降低1.03m,而第三层基坑回填后仅下降了0.33m。(7)运营阶段内,由于路面硬化截断了地下水接受降雨入渗补给与蒸发排泄途径,地下水仅可以向周边河流排泄,因此水位总体呈下降趋势,高水位区域渐渐消散。
[Abstract]:The excavation of the underground space of the Tianfu new airport is unique in its spatial structure and geological conditions. The underground space is multi-layered and intersecting traffic corridor: the first layer is the integrated transportation hub of buried depth -8m, the top elevation -9.42m of the second storey subway station, the floor elevation -11.1m, the third floor of the subway and the high speed railway station, and the underground space of the buried depth of the underground space. The new airport is located in the east of the Longquan mountain, west of the Tuojiang River, the hilly area in the field area, the dense water pool and the rich surface water. The formation of the new airport is located in the north-west wing of the nose like anticline in Jianyang, and the formation is a flat and gentle monoclinic sandstone mudstone interbedded stratum, although the water conditions in the red layer are provided. Relatively poor, but the local weak confined water exposed in the field makes the hydrogeological conditions complex in the field area. Combined with the above characteristics, the excavation of the underground space of the Tianfu new airport has a complicated influence on the seepage field, and the subtle differences in every step of the working condition affect the fluctuation of the seepage field. By using ModFlow to simulate the change of groundwater seepage field under different working conditions, and to boldly assume, reduce unnecessary construction steps, observe whether it will affect the huge change of the surrounding groundwater environment, and put forward the reasonable optimization measures for the construction scheme, and get the following conclusions according to a series of simulation results: (1 After field leveling, the small tributaries of Lianhua reservoir were landfilled, and the groundwater discharge area became the recharge runoff area after the landfill, and the relationship between the groundwater and Lianhua reservoir, the relationship between the Golden Chicken River and the lift river was not constant, but the intensity of the recharge runoff was weakened. The water level in the foundation pit should be reduced to the bottom of the foundation pit below 0.5m after the backfire of 0.04m. (2). The simulation results show that the influence radius of the dewatering of the foundation pit is directly proportional to the length of the filter tube, the influence radius of the three layer foundation pit precipitation is about 270~650m, and the waterstop curtain is far away from the surface water system. (3) the groundwater seepage will lead to the seepage of the foundation pit. The field form is torsional and provides a new way for groundwater discharge. The blocking effect of underground structures on groundwater is weakened. The interlayer structure of monoclinic sand mudstone leads to partial groundwater flow. The first and second layers of foundation pit precipitation will speed up the runoff speed of the underground structure at the water surface. (4) due to the repair of the third layer subway and the high speed railway station. It only reduced 7% of the original water crossing section, and intersected with the groundwater flow to a large angle. The building of the station has a weak intercepting effect on the groundwater. The groundwater seepage field is in the form of high water level at the surface of the surface of the surface of the underground structure and the low water level on the back surface, but there is no groundwater backwater. (5) the second layer subway station is located in the sandstone layer and over water. The cross section of the station is reduced by 19.87%, and the direction of the long axis of the station is 90 degrees with the subsurface laminar flow. Therefore, compared with the third story station, the barrier effect on the groundwater is slightly improved. When the second story station and the third station are at the same time, the groundwater level of the underground structures is higher than the back surface, and the two intercepts the northern part of the study area. The flow field of the high water level is in accordance with the outline of the underground structure. (6) compared with the backfilling of the third layer foundation pit, the upper backfilling of the second layer foundation pit is more favorable to the recovery of the groundwater seepage flow. After the foundation pit backfilling, the water table of the second floors of the station is reduced by 1.03m, and the third layer foundation pit backfill only drops in the 0.33m. (7) operation stage. Because the pavement hardening has truncated the groundwater to receive rainfall infiltration recharge and evaporation, the groundwater can only be excreted to the surrounding rivers, so the water level is generally declining, and the high water level area gradually dissipates.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：V351.1;P641.2

【参考文献】