Effect of ground fissure activity on groundwater level migration
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摘要: 为了研究地裂缝活动对地下水运移的影响,在西安市劳动路跨地裂缝试验场地开展水文地质抽水试验,采用Geo-Studio软件建立跨地裂缝水文地质试验模型,进行渗流分析。结果表明:地裂缝带上抽水井涌水量最大,地裂缝下盘稳定后的涌水量是上盘涌水量的3倍左右;地裂缝带含水层厚度最大、渗透性最好,下盘居中,上盘含水层厚度最小、渗透性最差;对于同一抽水井,抽水与加荷共同作用下产生的垂直位移是只有抽水作用情况下的4倍左右,对于群井,两者共同作用下产生的垂直位移是单独抽水作用下的2倍左右;在抽水作用下,由于地裂缝上下盘地层差异,孔隙水压力下降引起的有效应力增加会导致两侧土体的不均匀压缩,加剧了地裂缝的发展;无地裂缝时,各抽水井补给效果相差不大;有地裂缝时,根据不同的地层情况,地裂缝会表现出隔水和透水的两面性。Abstract: To study the influence of ground fissure activity on groundwater migration, hydrogeological pumping tests were conducted at the cross-ground fissure test site on Laodong Road in Xi’an, and a cross-ground fissure hydrogeological test model was established using Geo-Studio software for seepage analysis. The results show that the water inflow of the pumping well on the ground fissure zone is the largest, and the water inflow after the stability of the lower side of the ground fissure is roughly three times that after the stability of the hanging wall. The thickness of the aquifer in the ground fissure zone is the largest and the permeability of the ground fissure zone is the strongest, the footwall is in the middle, and the hanging wall has the smallest thickness and the worst permeability. For the same pumping well, the vertical displacement generated by the combined pumping action and load action is about 4 times that of the single pumping action. For a group of wells, the vertical displacement generated by the combined action of the two is about twice that of the single pumping action. Under the action of water pumping, due to the difference between the hanging wall and footwall of the ground fissure, the increase of effective stress caused by the decrease of pore water pressure will lead to the uneven compression of the soil on both sides and aggravate the development of the ground fissure. When there is no ground fissure, the recharge effect of each pumping well is similar; when there are ground fissures, according to different soil conditions, the ground fissures will show water resistance and permeability.
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Key words:
- ground fissure /
- pumping test /
- groundwater migration /
- pore water pressure /
- permeability coefficient
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表 1 4组抽水试验涌水量统计表
m3/d 落程 1号
抽水井2号
抽水井3号
抽水井群井 1号
抽水井2号
抽水井3号
抽水井小落程 125.34 118.13 45.04 67.6 67.6 38.7 中落程 156.82 156.82 51.96 106.7 106.7 45 大落程 202.25 186.34 51.96 130.29 143.19 38.7 表 2 1号抽水井计算出的渗透系数
落程 流量Q/(m3·d−1) 降深S/m 恢复时间t/min 渗透系数k/(m·d−1) k取值/(m·d−1) 小落程 125.34 4.59 1342 2.000 2.420 中落程 156.82 7.96 1572 2.790 大落程 202.25 17.71 1120 2.469 表 3 1,2,3号抽水井及群井的渗透系数
m/d 井号 1号
抽水井2号
抽水井3号
抽水井群井 1号
抽水井2号
抽水井3号
抽水井渗透系数 2.420 2.049 1.618 2.232 2.087 1.676 表 4 水文地质试验模型材料参数
层号 地层名称 重度
/(kN·m−3)弹性
模量
/MPa泊松比 体积压缩系数
/kPa−1饱和体积含水量
/m3渗透
系数
/(cm·s−1)1 填土 17.1 7 0.35 1.43×10-4 0.43 4.63×10−3 2 黄土 18.5 8 0.35 1.00×10-4 0.45 2.38×10−4 3 古土壤 19.8 10 0.35 1.25×10-4 0.42 1.62×10−4 4 中砂 19.1 4 0.25 2.50×10−5 0.55 3.19×10−2 5 粉质黏土 19.6 7 0.35 1.43×10-4 0.42 1.50×10−5 -
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