Karst water stratification discrimination and underground water level observation method
Technical Field
The invention relates to the discrimination of karst water stratification and the underground water level observation in the hydrogeological survey of a karst water distribution area, in particular to a karst water stratification discrimination and underground water level observation method.
Background
Karst water (cave water) is present in the erosive fractures and vugs of soluble rock formations. Soluble rock formations (including carbonate rock, gypsum rock, limestone conglomerate, etc.) act as voids in the aqueous karst medium, including diagenetic pores, vugs, tectonic fractures, vugs, eroded conduits, vugs, and eroded tunnels. The erosion action in the rock stratum is not uniform, the soluble rock stratum is used as an anisotropic non-uniform medium, and the permeability coefficient of different parts in the same aquifer is greatly changed. Therefore, no obvious boundary exists between the karst aquifer and the weakly permeable stratum, and the karst aquifer and the weakly permeable stratum can be mutually converted in specific functional occasions. Due to the characteristics of non-uniformity and vertical zonation of karst development, a multilayer aquifer structure is often formed in the karst aquifer, and the water levels of different horizon aquifers in a multilayer aquifer system cannot be accurately judged and correctly observed by adopting the conventional underground water monitoring instrument.
Finding out the karst underground water level has important scientific significance for comprehensively mastering the hydrogeological conditions of karst development areas, evaluating the karst development degree and researching the karst leakage problem. At present, most of karst water stratified water level observation methods are the conventional diving-confined water stratified water level observation methods, namely, the 'plugging measure' is adopted for observing the water levels of different aquifers, a non-target layer is plugged by using an anti-seepage material and then observation of the water level of the target layer is carried out, when the non-target layer is thick, a large amount of plugging materials are needed, the construction process is complicated, a large amount of labor and time cost is needed, and time is also needed for solidification of part of the plugging materials (such as concrete). Moreover, if the layered positions of the multilayer aquifer are more, the plugging scheme and the plugging process are very complicated. Therefore, the traditional method is high in cost in the aspect of layered water level observation, and low in overall observation efficiency. Meanwhile, the layered water level observation method taking the 'plugging measure' as a main means has irreversibility, namely once plugging is implemented, the original state of the aquifer is not possible to restore, and the influence on the aquifer is large. The plugging scheme needs to comprehensively and accurately know the aquifer, accurate square calculation and construction process are needed to support, if deviation occurs in the plugging scheme and the construction process, failure of layered water level observation is caused, the layered water level observation effect is influenced by the quality of the plugging material water stopping effect, the situations of mixed water and layered water which are unclear often occur, the disturbance to the aquifer is large, and the hydrological observation effect is poor.
Disclosure of Invention
The invention aims to provide a karst water stratification discrimination and underground water level observation method, which improves the working efficiency and reduces the capital investment, the labor and the time cost.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to a karst water stratification discrimination and underground water level observation method, which comprises the following steps:
step 1, constructing an exploration hole according to a karst water stratification position preliminarily judged by an underground water monitoring instrument, quantitatively monitoring and recording drilling fluid backwater data at the beginning and the end of each return footage in the exploration hole construction process according to each set return drilling scale, calculating the leakage amount of each return drilling fluid according to the drilling fluid backwater data, converting the leakage amount data into the leakage amount per unit meter, recording the leakage amount per unit meter and drawing a leakage amount data change curve per unit meter;
step 2, carrying out linear corrosion rate statistics on the rock core, obtaining linear corrosion rate data per unit meter and drawing a linear corrosion rate change curve per unit meter; linear corrosion rate per unit meter = cumulative development length of karst on the surface of a certain recurrent core/recurrent footage;
step 3, carrying out a pressurized water test in sections while carrying out the step 1 and the step 2; the water pressure test section is consistent with each secondary footage, the integral water permeability data of each secondary stratum are obtained, the water permeability data are converted into water permeability data per unit meter, and a water permeability data change curve per unit meter is drawn;
step 4, comparing the leakage data change curve per unit meter, the linear erosion rate change curve per unit meter and the water permeability data change curve per unit meter on the basis of the steps 1 to 3, and performing preliminary analysis on the waveform change of each curve; when the same trend change rule characteristics of each curve waveform are obvious or the change inflection points of the curve waveforms are close, carrying out layered judgment on the karst water aquifer, and then carrying out step 7;
step 5, on the basis of the step 4, when the amplitude variation difference of the waveform of the curve is too large or the same trend change rule characteristic of the original graph is not obvious and difficult to perform initial judgment, respectively performing normalization processing on leakage data per unit meter, linear corrosion rate data per unit meter and water permeability data per unit meter by using a Zscore function in MATLab, then respectively performing logarithmic function conversion with 10 as the base on three groups of data subjected to the normalization processing, drawing the three groups of data in the same coordinate system in the form of curves through the filtering method, then performing waveform change characteristic analysis on the three curves, extracting stratum water permeability change characteristics, and further performing layered judgment on the rock water layer;
step 6, when the same trend change rule characteristics of the curve waveform are obvious, directly carrying out layered discrimination on the karst water aquifer, and then carrying out step 7; when the same trend change rule of the curve waveform is still not obvious, performing optical imaging on the full-hole wall of the drill hole through the observation hole, analyzing and comprehensively judging the full-hole wall imaging of the karst aquifer, and simultaneously combining pressurized water test data to perform visual layering of the karst aquifer or recheck the accuracy of each primarily divided karst water layering layer result, and then performing step 7;
and 7, according to the karst water stratified layer position judgment result, utilizing a top pressure type water pressure test device to carry out stratified karst water observation, isolating different water-containing layers through a single or a plurality of expansion plugs, and realizing observation of different water-containing layer stratified water levels by matching with the arrangement of the drill rod water-permeable pipe sections at different water-containing layers.
The invention also includes: step 8, carrying out combined statistics and analysis on the layer division conditions of the adjacent observation holes in the same engineering area, and carrying out re-judgment on the division of the water-containing layer by combining the karst development phenomenon revealed by drilling holes or adit in the same engineering area; and 9, carrying out statistical analysis and arrangement on the layered water level data, and inputting the data into a geological comprehensive management database.
In step 1 of the invention, the drilling fluid backwater amount data from the beginning to the end of each return footage in the exploration hole construction process is quantitatively monitored and recorded according to the following steps:
step 1.1, arranging a water return pool beside an exploration hole, and arranging a scale in the water return pool from bottom to top, wherein the scale is used for measuring volume data of return water amount of drilling fluid in the water return pool; namely:
;
in the formula: vi-representing the drilling fluid return volume in the return tank at the ith moment;
a represents the length of the bottom of the backwater pool;
b represents the width of the bottom of the backwater pool;
hi-a reading indicating the return of drilling fluid in the return tank on the scale at the ith moment;
step 1.2, before the nth footage begins, measuring the volume of the drilling fluid backwater in the backwater tank, and using Vn1 represents; after the nth footage is finished and the drilling fluid backwater is stabilized, measuring the volume of the drilling fluid backwater in the backwater tank, and using V n2 represents;
step 1.3, obtaining the drilling fluid leakage amount of the nth footage through the calculation, wherein the formula is as follows:
in the formula: vnReturning-the drilling fluid return water amount at the end of the nth footage;
Vnleakage-the leakage amount of the drilling fluid in the nth footage process;
Vn1-the volume of the drilling fluid backwater in the backwater tank before the nth footage begins;
Vn2-the volume of the drilling fluid backwater in the backwater tank after the nth footage is finished;
x-nth footage and return depth;
r-radius of exploratory hole;
when V isnWhen the leakage =0, the stratum where the nth footage is located is impervious to water;
when V isnLeakage net>When the value is 0, the drilling fluid loss exists in the stratum where the nth footage is located, and the stratum water permeability is better if the numerical value is larger;
when V isnLeakage net<When the water permeability of the stratum is 0, the stratum is subjected to water outlet, and the water permeability of the stratum is better if the absolute value of a negative value is larger; when V isnWhen the leakage is negative, V is adopted when the leakage is converted into the leakage per unit meternThe absolute value of the leak is calculated.
In step 7 of the invention, the karst water stratified water level observation is carried out according to the following steps:
step 7.1, installing drill rod sections with plugging screw caps at the bottoms of drill rods, then connecting the drill rod sections section by section to lower the drill rod sections into exploration holes, installing the drill rod sections with water permeable holes at the middle positions of the stratums of target aquifers to be observed, using two drill rod sections with water pressing plugs attached to the outer peripheral surfaces, respectively connecting the two drill rod sections with the water pressing plugs attached to the upper and lower connecting ends of the drill rod sections with the water permeable holes, respectively enabling the upper and lower water pressing plugs to be located at the positions of the relative water-resisting layers at the upper parts and the lower parts of the target aquifers, respectively exposing the top ends of the drill rods to the ground and installing a three-way joint;
7.2, connecting the drilling platform with the top of the drill rod, and applying additional dynamic pressure to the drill rod through the self weight of the drilling platform or the rotation of a rotating shaft of a drilling machine to expand the two water pressing plugs so as to realize the water seal between the target aquifer and the relative water barriers at the upper part and the lower part of the aquifer;
and 7.3, disturbing the water injection of the inner cavity of the drill rod through the three-way head at the top of the drill rod, and then placing a measuring line in the inner cavity of the drill rod to measure the stable water level, wherein the stable water level of the inner cavity of the drill rod is the water level of the target aquifer to be observed.
In the step 1 of the invention, each repeated drilling depth is not a fixed value, can be selected from 3.0m to 5.0m, and can be properly adjusted according to the geological conditions of the field karst.
The invention has the advantages that the invention is mainly embodied in the following aspects:
1. the cost is reduced and the efficiency is improved.
Compared with the traditional method, the method saves the special observation hole arrangement, the purchase of a large amount of plugging materials and the complex plugging construction means; according to the invention, observation holes are not constructed independently, the existing geological survey means and results are combined, the efficiency and accuracy of water-containing layer position discrimination are improved by using a water-pressurizing test device, the convenience of karst water layering water level observation is improved, and a set of efficient, convenient and systematic karst water layering judgment and underground water level observation method is summarized.
2. And the observation means is improved, and green water level observation is realized.
The convenience and flexibility of the operation method are improved, the natural state of each water-containing layer is not influenced, the disturbance to the water-containing layer is reduced while the karst water layering water level observation effect is improved, and green layering water level observation is realized.
3. The systematicness and the popularization of the karst water stratification water level observation method are enhanced.
The method provides systematic karst water stratification discrimination and underground water level observation, has high reliability and flexibility, and has good popularization and reproducibility.
Drawings
FIG. 1 is a schematic diagram of a method for observing the water level of a designated horizon of a double-expansion plug of a karst water multi-aquifer.
FIG. 2 is a schematic diagram of a layered water level observation method of a karst water double-aquifer single-expansion plug.
Detailed Description
The following describes embodiments of the present invention in detail with reference to the drawings, which are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are provided, but the scope of the present invention is not limited to the following embodiments.
Example 1:
as shown in fig. 1, the method for identifying a karst water layer and observing an underground water level according to the present invention is described by taking a geological structure of four water-containing layers as an example:
step 1, constructing exploration holes according to karst water stratification positions preliminarily judged by an underground water monitoring instrument, setting each recurrent drilling scale to be 3.0m, quantitatively monitoring and recording drilling fluid backwater data when each recurrent footage starts and ends in the exploration hole construction process, calculating the leakage amount of each recurrent drilling fluid according to the drilling fluid backwater data, converting the leakage amount data into the leakage amount per unit meter, recording the leakage amount data per unit meter and drawing a leakage amount data change curve per unit meter; the method comprises the following specific steps:
step 1.1, arranging a
water return pool 2 beside an exploration hole 1, and arranging a scale in the
water return pool 2 from bottom to top, wherein the scale is used for measuring volume data of return water volume of drilling fluid in the
water return pool 2; namely:
;
in the formula: vi-representing the drilling fluid return volume in the return tank at the ith moment;
a represents the length of the bottom of the backwater pool;
b represents the width of the bottom of the backwater pool;
hi-a reading indicating the return of drilling fluid in the return tank on the scale at the ith moment;
step 1.2, before the nth footage begins, measuring the volume of the drilling fluid backwater in the backwater pool 2, and using Vn1 represents; after the nth footage is finished and the drilling fluid backwater is stable, measuring the volume of the drilling fluid backwater in the backwater pool 2, and using V n2 represents;
step 1.3, obtaining the drilling fluid leakage amount of the nth footage through the calculation, wherein the formula is as follows:
in the formula: vnReturning-the drilling fluid return water amount at the end of the nth footage;
Vnleakage-the leakage amount of the drilling fluid in the nth footage process;
Vn1-the volume of the drilling fluid backwater in the backwater tank before the nth footage begins;
Vn2-the volume of the drilling fluid backwater in the backwater tank after the nth footage is finished;
x-nth footage and return depth;
r-radius of exploratory hole;
when V isnWhen the leakage =0, the stratum where the nth footage is located is impervious to water;
when V isnLeakage net>When the value is 0, the drilling fluid loss exists in the stratum where the nth footage is located, and the stratum water permeability is better if the numerical value is larger;
when V isnLeakage net<When the water permeability of the stratum is 0, the stratum is subjected to water outlet, and the water permeability of the stratum is better if the absolute value of a negative value is larger; when V isnWhen the leakage is negative, V is adopted when the leakage is converted into the leakage per unit meternThe absolute value of the leak is calculated.
Step 2, carrying out linear corrosion rate statistics on the rock core, obtaining linear corrosion rate data per unit meter and drawing a linear corrosion rate change curve per unit meter; linear corrosion rate per unit meter = cumulative development length of karst on the surface of a certain recurrent core/recurrent footage;
step 3, carrying out a pressurized water test in sections while carrying out the step 1 and the step 2; the water pressure test section is consistent with each secondary footage, the integral water permeability data of each secondary stratum are obtained, the water permeability data are converted into water permeability data per unit meter, and a water permeability data change curve per unit meter is drawn;
step 4, comparing the leakage data change curve per unit meter, the linear erosion rate change curve per unit meter and the water permeability data change curve per unit meter on the basis of the steps 1 to 3, and performing preliminary analysis on the waveform change of each curve; and (3) when the characteristics of the same trend change rule of each curve waveform are obvious or the positions of inflection points of the curve waveform change are close, performing layered judgment on the karst water aquifer, and then performing the step 7.
Step 5, on the basis of the step 4, when the amplitude variation difference of the waveform of the curve is too large or the same trend change characteristic of the original graph is not obvious and difficult to perform initial judgment, respectively performing normalization processing on leakage data per unit meter, linear corrosion rate data per unit meter and water permeability data per unit meter by using a Zscore function in MATLab, then respectively performing logarithmic function conversion with 10 as the base on three groups of data subjected to the normalization processing, drawing the three groups of data in the same coordinate system in a curve form through the filtering method, then performing waveform change characteristic analysis of three curves, extracting stratum water permeability change characteristics, and further performing layered judgment on a rock water layer;
step 6, when the same trend change rule characteristics of the curve waveform are obvious, directly carrying out layered discrimination on the karst water aquifer, and then carrying out step 7; when the same trend change rule of the curve waveform is still not obvious, performing optical imaging on the full-hole wall of the drill hole through the observation hole, analyzing and comprehensively judging the full-hole wall imaging of the karst aquifer, and simultaneously combining pressurized water test data to perform visual layering of the karst aquifer or recheck the accuracy of each primarily divided karst water layering layer result, and then performing step 7;
and 7, according to the result of judging the layered position of the karst water, utilizing a top pressure type water pressure test device to observe layered karst water, isolating different water-containing layers in the exploration hole 1 through two water pressure plugs 7 (expansion plugs), and realizing the observation of the layered water levels of different water-containing layers by matching the arrangement of the drill rod water-permeable pipe sections 5 at different water-containing layers. Wherein, the observation of the layered position of the karst water is carried out according to the following steps:
step 7.1, installing the drill rod section 4 with the plugging screw cap 3 at the bottom of the drill rod, then connecting the drill rod sections section by section to lower each drill rod section into the exploration hole 1, installing the drill rod section 5 with the water permeable hole at the middle position of the stratum where the target aquifer 6 (the third aquifer in the embodiment) to be observed is located, respectively connecting the two drill rod sections 8 and 9 with the water pressurizing plugs 7 to the upper and lower connecting ends of the drill rod section 5 with the water permeable hole, respectively enabling the upper and lower water pressurizing plugs 7 to be located at the position of the relative water-resisting layer 10 at the upper part of the target aquifer 6 and the position of the relative water-resisting layer 11 at the lower part of the target aquifer 6, respectively exposing the top end of the drill rod to the;
7.2, connecting the drilling platform 12 with the top of the drill rod, and applying additional dynamic pressure to the drill rod through the self weight of the drilling platform 12 or the rotation of a rotating shaft of a drilling machine to expand the two water pressing plugs 7 so as to realize the sealing between the target aquifer 6 and the relative water barriers 10 and 11 on the upper part and the lower part of the target aquifer;
and 7.3, disturbing the water injection of the inner cavity of the drill rod through the three-way head at the top of the drill rod, and then placing a measuring line in the inner cavity of the drill rod to measure the stable water level, wherein the stable water level 13 of the inner cavity of the drill rod is the water level of the target aquifer to be observed.
Step 8, carrying out combined statistics and analysis on the layer division conditions of the adjacent observation holes in the same engineering area, and carrying out re-judgment on the division of the water-containing layer by combining the karst development phenomenon revealed by drilling holes or adit in the same engineering area;
and 9, carrying out statistical analysis and arrangement on the layered water level data, and inputting the data into a geological comprehensive management database.
Example 2:
as shown in fig. 2, the geological structure of the invention in which the karst water layer is two water-containing layers is shown, and the implementation steps are different from those of example 1 only in that the number of the water pressure plugs 7 used is one. The target aquifer 6 that this embodiment needs to be observed is the second floor, and the upper and lower part on second floor is relative water barrier, consequently, only needs to connect the drilling rod section 8 that the cover was equipped with pressurized-water plug 7 in the upper end of the hole drilling rod section 5 that permeates water, can accomplish the stable water level 13 of target aquifer 6 and observe.