JPH0730573B2 - Correction method for uneven settlement of aboveground tanks due to lowered groundwater level - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an above-ground tank non-uniform settlement correction method for correcting the subsidence amount of a ground type tank caused by a decrease in groundwater level so that the total subsidence amount is the same. is there.

(Prior Art) In an aboveground tank, if the tank undergoes uneven settlement, the tank may tilt. Since such an inclination hinders the taking out of stored materials and the detection of the remaining amount, it is necessary to make the sinking amounts of the entire tank substantially equal.

As a method of correcting the difference in the subsidence amount of the tank, it has been conventionally adopted to elevate / move the tank and externally process the tank foundation.

(Problems to be Solved by the Invention) With the above-described conventional method, it is necessary to temporarily withdraw the stored material in the tank and temporarily suspend the use of the tank at the time of correction. During that time, it is necessary to store the stored material in the tank in another place, and a great deal of labor is required for the work and securing the storage place.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a ground-based tank non-uniform settlement correction method by lowering the groundwater level that does not require stopping the tank.

(Means for Solving Problems) The above-mentioned ground tank level subsidence correction method for lowering groundwater level according to the present invention is a method in which a pumping well is set in the ground on the high level side, which is the one with the less groundwater tank subsidence The water injection wells are installed in the ground on the lower side, which is the larger one, and the groundwater is pumped up from the pumping well, the water is injected from the water injection well, and the groundwater level is observed and pumping and water injection are stopped occasionally. Draw a water table curve based on the amount of rebound from the condensate test performed by the water condensate test, and continue pumping and water injection while controlling the water table curve to match the design value. It is characterized by lowering the groundwater level on one side and lowering the groundwater level on the higher level side to sink the higher level side so that the subsidence amount of the entire aboveground tank is the same.

It is possible to install a pumping well in the ground on the high-level side to pump up groundwater, lower the groundwater level on the high-level side, and sink the high-level side to correct the differential settlement, but groundwater on the high-level side can be corrected. When the pump is pumped up, the groundwater level on the low level side will decrease with time, and the low level side will also sink, if not the subsidence amount on the high level side, and the entire tank will sink. On the other hand, if the subsidence amount of the whole tank becomes large, it will adversely affect the pipes for feeding and discharging the stored products and the peripheral structures. Therefore, it is desirable that the subsidence amount of the whole tank is small. Therefore, in the present invention, a method is adopted in which water is pumped from the low-level side together with pumping from the high-level side, and only the high-level side groundwater level is lowered while maintaining the low-level side groundwater level. That is, it is a method of maintaining the groundwater level on the low-level side as much as possible and increasing the difference in groundwater level between the low-level side and the high-level side compared to before construction, so that only the high-level side is subsided. Even though it only lowers the groundwater level on the high-level side, the groundwater on the high-level side and the groundwater on the low-level side are not cut off, so it is unavoidable that the water level difference between the two will decrease over the years. Absent.

Various works such as installation of pumping well, water injection well, observation well, etc., pumping, water injection, observation, and measurement in this invention can be performed independently of the tank while the tank is in use. There is no need to suspend the use of the tank at all.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

In FIG. 1, A is a tank foundation ground, which is composed of a sandy soil layer 1 and a cohesive soil layer 2. Groundwater exists in the tank foundation ground A, and 3 in the figure indicates the groundwater level.

In the figure, reference numeral 4 designates a ground type tank, where the front left is the high side B with a small subsidence and the right front is the low side C with a large subsidence.
A plurality of pumping wells 5 are provided in the ground A on the high side B of this ground tank 4, and a plurality of water injection wells 7 are provided in the ground A on the low side C.
Drill each. Drill each well well deeper than groundwater level 3. Incidentally, reference numeral 6 in the figure denotes an existing structure in the vicinity.

Pump up groundwater from the pumping well 5 and observe the groundwater level 3 which decreases with pumping. On the other hand, the groundwater level 3 is also observed on the water injection well 7 side, and water is injected so that the groundwater level 3 does not decrease. When the groundwater level 3 on the pumping well 5 side drops, the high side B of the tank 4 sinks. Observation of groundwater level 3 and sometimes,
Draw a water surface curve based on the groundwater level 3 by grasping the amount of rebound in a condensate test conducted after stopping pumping and water injection, and continue pumping and water injection while controlling the water surface curve to match the design value. After confirming that the measured value of the sinking condition on the high-level side B of the tank 4 and the controlled water surface curve match the design value, the correction work is completed, and the well is closed.

3 and 4 show an example in which, in addition to the pumping well 5 and the water injection well 7, a water blocking wall 8 is installed on the existing structure 6 side in the surroundings. When the groundwater layer is partitioned by the impermeable wall 8 in this manner, the decrease in the groundwater level on the high-level side B of the tank 4 does not affect the groundwater below the surrounding existing structure 6.

(Effects of the Invention) Since the present invention is configured as described above, it has the following effects.

(1) The correction work can be performed while the tank is in operation, which does not require much labor and can be easily performed.

(2) Since the lower part of the tank hardly sinks, the sinking amount of the entire tank is small.

[Brief description of drawings]

1 is a vertical sectional view of an embodiment of the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a vertical sectional view of another embodiment, and FIG. 4 is a plan view thereof. A: Tank foundation ground, B: High level side, C: Low level side, 1 ... Sandy soil layer, 2 ... Cohesive soil layer, 3 ... Groundwater level, 4 ... Ground tank, 5 …… Pumping well, 6 …… Existing structure, 7 …… Water injection well, 8 …… Impermeable wall.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaru Hino 1-2-7 Moto Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. (72) Inventor Hisatsu Hirano 1-2-7 Moto-Akasaka, Minato-ku, Tokyo No. within Kashima Construction Co., Ltd. (56) Reference Japanese Patent Laid-Open No. 53-89014 (JP, A) Shoukai 55-24371 (JP, U)

Claims (1)

[Claims] 1. A pumping well is installed on the ground on the high level side, which has a smaller subsidence of the aboveground tank, and a water injection well is installed on the ground on the low level side, which has a larger subsidence. Draw a water table curve by drawing up ground water, injecting water from the water injection well, and observing the ground water level and grasping the rebound amount by the condensate test performed by stopping pumping and water injection from time to time. Continued pumping and water injection while controlling to match the design value, lowering the groundwater level on the high level side while maintaining the groundwater level on the low level side to sink the high level side, and the amount of subsidence of the entire ground tank The above ground type tank uneven settlement correction method by lowering groundwater level.