【摘要】：古河道型地下水庫是開發(fā)利用古河道淺層淡水基礎上發(fā)展起來的,其試圖人為利用古河道砂體作為調(diào)蓄庫容,增加可利用水資源量。在沖積平原地區(qū),古河道通常是地下水儲存和運移的主要通道,對于建設地下水庫而言,古河道為調(diào)蓄水資源,進行地下水回灌,修復地下水位起到關鍵性作用。彌河下游沖洪積扇內(nèi)因來水量平枯不均,地表水攔蓄工程較少,致使地表水利用率較低,區(qū)域內(nèi)地下水超采嚴重,地下水位大幅下降,現(xiàn)已形成多個區(qū)域性大型漏斗區(qū),加之北部咸水水頭與區(qū)域內(nèi)淡水水頭差日益增大,依托古河道良好的地層條件,北部咸水向內(nèi)陸含水層的入侵現(xiàn)象愈發(fā)嚴重。為縮減地下水漏斗區(qū),抬升區(qū)域地下水位,利用地下壩體阻止咸水入侵、阻截淡水入海,現(xiàn)擬借助古河道中沉積的砂、礫石等多孔介質(zhì)作為儲水空間來建設地下水庫,并引調(diào)地表水體進行蓄灌,從而防止北部咸水的進一步入侵。因此對于庫區(qū)內(nèi)古河道結(jié)構(gòu)的研究是建設古河道型地下水庫的一項重要內(nèi)容,古河道位置、埋藏深度及厚度等特征的查明可為地下水庫建設的位置、規(guī)模、結(jié)構(gòu)及地下防滲墻關鍵技術參數(shù)等研究提供依據(jù)。本論文主要研究內(nèi)容及工作量如下:(1)通過收集彌河下游沖洪積扇地區(qū)的地形地貌、水文地質(zhì)、鉆孔巖性記錄及粒度分析等資料,查明研究區(qū)內(nèi)古河道形成與發(fā)育條件及巖性等特征參數(shù),明確古河道的分布特征和富水性動態(tài)變化特征。(2)根據(jù)現(xiàn)場地電條件,在研究區(qū)布置32條東西向高密度電阻率成像數(shù)據(jù)采集測線進行掃描測量,每條測線長378m,測線西起臺頭鎮(zhèn)付家莊村,東到田柳鎮(zhèn)王高八村以東,全長12096m;并在能反映古河道砂層存在的測線中采集24個測深點進行電測深曲線繪制,獲得巖體電特性參數(shù)信息;(3)將采集的野外實驗數(shù)據(jù)進行數(shù)據(jù)預處理、反演計算及繪圖等工作,得到二維高密度電阻率圖像和電測深曲線圖,重點從電阻率電特性參數(shù)分析巖體的空間結(jié)構(gòu)特征,研究古河道位置、埋深等信息。通過以上研究,取得了如下研究成果:(1)研究區(qū)內(nèi)古河道整體上是以高阻值電阻率體現(xiàn),在未固結(jié)成巖區(qū)其電阻率值在20-40Ω·m范圍內(nèi),巖性以細砂、粉細砂為主,在局部固結(jié)成巖區(qū),電阻率值可達幾百歐姆·米;圍巖以低阻值電阻率體現(xiàn),電阻率值在0-20Ω·m范圍內(nèi),巖性以地表覆蓋土層和黏土層為主。(2)基于二維高密度電阻率圖像分析,該段古河道呈WS—EN走向,東西寬約1400m,東西岸位置較明確;砂層在河道中段埋藏深度較大,兩端埋藏深度較小,呈大“U”字型分布,該分布極具典型河床特性,砂層厚度橫向變化符合古河床動力學產(chǎn)物特征;砂層周邊解譯出殘留黏土塊堆積,黏土塊的存在有的對砂層的堆積有明顯的制約作用,有的促使形成良好的砂層沉積區(qū),為進一步明確古河床沉積的形態(tài)和規(guī)律具有重要意義。(3)基于電測深曲線分析,古河道富集帶電阻率值整體呈三段走勢,表層電阻率值大多呈緩平或下降趨勢,判斷為黏土覆蓋層;中間曲線呈上升趨勢,電阻率值增加,判斷為砂層反映;底部曲線緩平或下降,判斷多為黏土層或砂質(zhì)黏土和粘質(zhì)砂土。
[Abstract]:The ancient channel type underground reservoir is developed on the basis of the development and utilization of the shallow fresh water of the ancient river channel, which is an attempt to make the use of the ancient river sand body as the storage capacity and increase the amount of available water resources. In the alluvial plain area, the ancient river channel is usually the main channel of underground water storage and migration. For the construction of the underground reservoir, the paleochannel is a key role in regulating the water resources, carrying out groundwater recharge and repairing the groundwater level. The internal cause of water and water in the alluvial fan in the lower reaches of the Yuhe River is uneven, and the surface water retaining works are less, so that the utilization of surface water is low, the groundwater in the area is extremely serious, the groundwater level is greatly reduced, and a plurality of regional large-scale funnel areas are formed. In addition, the difference of fresh water head in the water head of the north and the water head in the area is increasing, and the intrusion of the salt water to the inland aquifer becomes more serious depending on the favorable formation conditions of the ancient river channel. in ord to reduce that water level of the underground water funnel and raise the groundwater level of the area, the underground dam body is utilized to prevent the salt water intrusion, the water is intercepted and the fresh water enters into the sea, and the underground reservoir is constructed by using a porous medium such as sand and gravel deposited in the old river channel as a water storage space, and the surface water body can be used for storage and irrigation, so as to prevent the further invasion of the northern brackish water. Therefore, the research on the structure of the ancient river channel in the reservoir area is an important part of the construction of the ancient channel type underground reservoir, which can provide the basis for the research of the location, scale, structure of the underground reservoir and the key technical parameters of the underground anti-seepage wall. The main contents and workload of this thesis are as follows: (1) The characteristics of the formation and development conditions and the lithology of the paleochannel in the study area are identified by collecting data such as the topography, the hydrogeology, the drilling lithology and the grain size analysis of the alluvial fan area in the downstream of the Yuhe River. The distribution characteristics and the water-rich dynamic characteristics of the ancient river channel are defined. (2) According to the on-site electrical conditions, 32 east-west high-density resistivity imaging data acquisition and measurement lines are arranged in the study area for scanning and measurement, and the length of each test line is 378m, and the west of the line of measurement is in the village of Jiazhuang, and the east to the east of the eight-village-high-eight village in the town of Liuliu Town, and the total length is 12096m; and collecting 24 sounding points in the measuring line which can reflect the existence of the sand layer of the ancient river, and drawing the electric sounding curve to obtain the parameter information of the electrical property of the rock mass; and (3) carrying out data preprocessing, inversion calculation and drawing and the like of the collected field experimental data, A two-dimensional high-density resistivity image and an electric sounding curve are obtained, and the spatial structure characteristics of the rock mass are analyzed, such as the location of the ancient river channel, the depth of the burial, and the like. Through the above research, the following research results have been obtained: (1) The whole river channel in the study area is characterized by high resistance, and the resistivity value of the unconsolidated diagenetic area is in the range of 20-40惟 路 m, and the lithology is dominated by fine sand and fine sand, and in the local consolidation diagenetic area, The resistivity value can reach a few hundred ohms 路 m; the resistivity of the surrounding rock is represented by low resistance, and the resistivity value is in the range of 0-20 惟 路 m, and the lithology is dominated by the surface covering soil layer and the clay layer. (2) Based on the two-dimensional high-density resistivity image analysis, the paleochannel of this section is in the direction of WS-EN, the east and west is about 1400m, and the location of the east and west is clear; the depth of the sand layer in the middle of the channel is large, the buried depth of the two ends is small, and the large-鈥淯鈥，

本文編號：2391110