單井涌水量問題的試驗(yàn)和數(shù)值模擬研究
發(fā)布時(shí)間：2018-10-09 17:47
【摘要】：在水文地質(zhì)調(diào)查中,單井涌水量通常用作劃分富水性等級的指標(biāo),以反映含水層產(chǎn)出地下水的能力。通常用規(guī)定口徑、規(guī)定降深的出水量來表征單井涌水量。單井涌水量受到抽水井本身特性、含水層結(jié)構(gòu)、地下水補(bǔ)給條件以及抽水試驗(yàn)操作方式等因素的影響。一般用三個(gè)落程穩(wěn)定井流抽水試驗(yàn)獲得單井涌水量。單位涌水量是指單位降深對應(yīng)的單井涌水量。針對截取側(cè)向徑流的抽水井,蘭太權(quán)提出一個(gè)解釋單位涌水量的公式,認(rèn)為“單位涌水量就是導(dǎo)水系數(shù)”(q=T),并以砂箱試驗(yàn)的結(jié)果作為證據(jù)。然而,這個(gè)等式的推導(dǎo)過程缺少嚴(yán)謹(jǐn)?shù)乃畡?dòng)力學(xué)基礎(chǔ)。砂箱試驗(yàn)的邊界條件等價(jià)于含有1個(gè)或2個(gè)定水頭邊界的矩形承壓含水層,從理論上表明單位涌水量與導(dǎo)水系數(shù)成正比,而比例系數(shù)(q/T)取決于含水層的形狀(D/L)和抽水井的半徑(rw)。在特定條件下,含水層和抽水井的尺寸可以造成單位涌水量與導(dǎo)水系數(shù)相等的情況,蘭太權(quán)發(fā)表于文獻(xiàn)中的2組砂箱試驗(yàn)恰好符合這種條件,但并不能證明q=T具有普適性。新的砂箱試驗(yàn)避免了幾何尺寸的這種特殊組合,得到了顯著偏離q=T的結(jié)果。通過PMWIN軟件對單位涌水量問題進(jìn)行數(shù)值模擬研究,結(jié)果表明單位涌水量與導(dǎo)水系數(shù)的比值q/T取決于含水層的尺寸(D/L)、抽水井的半徑(rw)、非完整井穿透含水層的深度(l/M)和抽水井的位置(x/L,y/L)等因素,但是跟水力梯度沒有關(guān)系。將這些影響因素特殊組合在一起可能出現(xiàn)單位涌水量等于導(dǎo)水系數(shù)的情況,但修改其中一個(gè)影響因素就會(huì)得到偏離q=T的結(jié)果。評估地下水可開采量有簡單評估法和模擬評估法兩種策略:簡單評估法直接套用單位涌水量與最大允許降深的乘積代表地下水可開采量;模擬評估法是通過數(shù)值模擬來預(yù)測最大允許降深約束下的抽水方案。本文以秦皇島石門寨水源地為例進(jìn)行了對比研究。為了防止巖溶塌陷,取抽水井地下水位不低于灰?guī)r頂部作為約束條件,簡單評估法得到的地下水可開采量為101341 m3/d,模擬評估法得到的可開采量為31300 m3/d,兩者相差甚大。所以,簡單利用單井涌水量評估可開采量這種傳統(tǒng)策略并不可靠。模擬評估法得到抽水孔單位涌水量與導(dǎo)水系數(shù)的比值q/T為0.20~0.71,也顯著偏離q=T的條件。
[Abstract]:In hydrogeological survey, single well water discharge is usually used as an index to classify the level of rich water to reflect the ability of aquifer to produce groundwater. A single well water inflow is usually characterized by a specified caliber and a reduced depth of water. The water inflow of single well is affected by the characteristics of pumping well, aquifer structure, groundwater recharge condition and pumping test operation. The water inflow of single well is usually obtained by pumping test of three stable wells. Unit water inflow is a single well water inflow corresponding to unit depth reduction. In view of the pumping wells intercepting lateral runoff, Lan Taiquan puts forward a formula to explain the unit water inflow, which holds that "unit water inflow is the coefficient of water conductivity" (QT), and the results of sand box test are taken as evidence. However, the derivation of this equation lacks a rigorous hydrodynamic basis. The boundary condition of sand box test is equivalent to the rectangular confined aquifer with one or two fixed head boundaries. Theoretically, it is shown that the unit water inflow is proportional to the conductivity coefficient, while the proportional coefficient (Q / T) depends on the shape of the aquifer (D / L) and the radius of the pumping well (rw). Under certain conditions, the size of aquifer and pumping well can make the unit water inflow equal to the coefficient of water conductivity. The two sets of sand box tests published by Lan Taiquan in the literature just meet this condition, but it can not be proved that QT is universal. The new sand box test avoids this special combination of geometric dimensions and obtains a significant deviation from QT. The numerical simulation of unit water inflow is carried out by PMWIN software. The results show that the ratio Q / T of unit inflow to conductivity depends on the size of aquifer (D / L), the depth (l / M) of (rw), nonholonomic well penetrating aquifer and the location of pumping well (x / L y / L), but it has no relation with hydraulic gradient. When these factors are combined together, it is possible that the unit water inflow is equal to the coefficient of water conductivity, but if one of the factors is modified, the result of deviation from QT can be obtained. There are two strategies for evaluating groundwater recoverable quantity: simple evaluation method and simulation evaluation method: simple evaluation method directly applies the product of unit discharge and maximum allowable depth to represent groundwater exploitable amount; The simulation evaluation method is used to predict the pumping scheme with maximum allowable depth reduction constraint by numerical simulation. This paper takes the Shimenzhai water source area of Qinhuangdao as an example to make a comparative study. In order to prevent karst collapse, the groundwater level of pumping well is not lower than the top of limestone as the constraint condition. The recoverable amount of groundwater obtained by simple evaluation method is 101341 m3 / d, and that obtained by simulation evaluation method is 31300 m3 / d, which is quite different between the two methods. Therefore, it is not reliable to simply use the single well water inflow to estimate the recoverable capacity. The ratio Q / T of unit inflow and conductivity of pumping hole is 0.200.71, which deviates significantly from the condition of QT.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：P641.7
本文編號：2260208
[Abstract]:In hydrogeological survey, single well water discharge is usually used as an index to classify the level of rich water to reflect the ability of aquifer to produce groundwater. A single well water inflow is usually characterized by a specified caliber and a reduced depth of water. The water inflow of single well is affected by the characteristics of pumping well, aquifer structure, groundwater recharge condition and pumping test operation. The water inflow of single well is usually obtained by pumping test of three stable wells. Unit water inflow is a single well water inflow corresponding to unit depth reduction. In view of the pumping wells intercepting lateral runoff, Lan Taiquan puts forward a formula to explain the unit water inflow, which holds that "unit water inflow is the coefficient of water conductivity" (QT), and the results of sand box test are taken as evidence. However, the derivation of this equation lacks a rigorous hydrodynamic basis. The boundary condition of sand box test is equivalent to the rectangular confined aquifer with one or two fixed head boundaries. Theoretically, it is shown that the unit water inflow is proportional to the conductivity coefficient, while the proportional coefficient (Q / T) depends on the shape of the aquifer (D / L) and the radius of the pumping well (rw). Under certain conditions, the size of aquifer and pumping well can make the unit water inflow equal to the coefficient of water conductivity. The two sets of sand box tests published by Lan Taiquan in the literature just meet this condition, but it can not be proved that QT is universal. The new sand box test avoids this special combination of geometric dimensions and obtains a significant deviation from QT. The numerical simulation of unit water inflow is carried out by PMWIN software. The results show that the ratio Q / T of unit inflow to conductivity depends on the size of aquifer (D / L), the depth (l / M) of (rw), nonholonomic well penetrating aquifer and the location of pumping well (x / L y / L), but it has no relation with hydraulic gradient. When these factors are combined together, it is possible that the unit water inflow is equal to the coefficient of water conductivity, but if one of the factors is modified, the result of deviation from QT can be obtained. There are two strategies for evaluating groundwater recoverable quantity: simple evaluation method and simulation evaluation method: simple evaluation method directly applies the product of unit discharge and maximum allowable depth to represent groundwater exploitable amount; The simulation evaluation method is used to predict the pumping scheme with maximum allowable depth reduction constraint by numerical simulation. This paper takes the Shimenzhai water source area of Qinhuangdao as an example to make a comparative study. In order to prevent karst collapse, the groundwater level of pumping well is not lower than the top of limestone as the constraint condition. The recoverable amount of groundwater obtained by simple evaluation method is 101341 m3 / d, and that obtained by simulation evaluation method is 31300 m3 / d, which is quite different between the two methods. Therefore, it is not reliable to simply use the single well water inflow to estimate the recoverable capacity. The ratio Q / T of unit inflow and conductivity of pumping hole is 0.200.71, which deviates significantly from the condition of QT.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：P641.7
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