KR20160059051A - A casing for the soil survey of a site of the seabed and method for predicting support force of the casing with the passage of time - Google Patents

A casing for the soil survey of a site of the seabed and method for predicting support force of the casing with the passage of time Download PDF

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Publication number
KR20160059051A
KR20160059051A KR1020140160075A KR20140160075A KR20160059051A KR 20160059051 A KR20160059051 A KR 20160059051A KR 1020140160075 A KR1020140160075 A KR 1020140160075A KR 20140160075 A KR20140160075 A KR 20140160075A KR 20160059051 A KR20160059051 A KR 20160059051A
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KR
South Korea
Prior art keywords
casing
ground
inner casing
side pressure
time
Prior art date
Application number
KR1020140160075A
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Korean (ko)
Inventor
이종휘
Original Assignee
현대중공업 주식회사
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Priority to KR1020140160075A priority Critical patent/KR20160059051A/en
Publication of KR20160059051A publication Critical patent/KR20160059051A/en

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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D1/00—Investigation of foundation soil in situ
    • E02D1/02—Investigation of foundation soil in situ before construction work
    • E02D1/027—Investigation of foundation soil in situ before construction work by investigating properties relating to fluids in the soil, e.g. pore-water pressure, permeability
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/02—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning
    • G01L9/04—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in ohmic resistance, e.g. of potentiometers, electric circuits therefor, e.g. bridges, amplifiers or signal conditioning of resistance-strain gauges
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2250/00—Production methods
    • E02D2250/0061—Production methods for working underwater
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2600/00—Miscellaneous
    • E02D2600/10—Miscellaneous comprising sensor means

Abstract

An underwater ground handling casing according to an embodiment of the present invention includes an inner casing having an inner hollow cylindrical shape; An outer casing into which the inner casing is inserted and exposes a part of the outer circumferential surface of the inner casing to the outside; And a plurality of side pressure measuring sensors attached to an outer circumferential surface of the inner casing exposed to the outside of the outer casing.

Description

Technical Field [0001] The present invention relates to a method for predicting bearing capacity of a casing for underwater ground handling according to underwater ground handling casing and time lag effect,

The present invention relates to a method of predicting the bearing capacity of an underwater ground handling casing due to underwater ground handling casing and time lapse effect.

When constructing structures on the seabed or in the sea, the stability of the foundation ground should be checked to cope with the load of the structure or natural disasters.

Therefore, in order to acquire the design ground constants at the early stage of the ground survey, a ground penetration test such as a standard penetration test or a cone penetration test is generally performed.

Since the upper load is supported by the pile installed in the foundation ground, it is necessary to measure the strength and deformation characteristics of each pile in advance by measuring the bearing capacity of the pile installed on the foundation foundation and the frictional force of the foundation.

The bearing capacity of the pile is calculated by the bearing capacity of the pile at the tip of the pile and the frictional force at the surface of the pile. At this time, the bearing capacity of the pile can be ignored in the clay ground such as the seabed ground, and the bearing capacity of the pile can be calculated by the surface friction force.

In this case, when the pile is built in the ground, the ground will undergo extreme changes due to the intrusion of the pile.

The main contents of the ground change are various such as ground stress change and pore water pressure change, and such changes will change again with the passage of time from the installed point of the pile.

Thus, the bearing capacity of the pile varies with the time elapsed since the pile was installed. For example, there may occur a phenomenon in which the bearing capacity increases after a certain period of time has elapsed since the pile has been introduced into the ground, and a relaxation phenomenon in which the bearing capacity is decreased after a predetermined time has elapsed may occur.

Therefore, it is necessary to confirm the bearing capacity of the pile over time in various ground conditions.

However, when the pile is installed on the ground, not the ground, there is a problem that the long-term operation of the pile loading test for the dynamic pile load test is difficult considering the cost aspect.

Therefore, in the ground survey using the initial barge, it is necessary to plan the construction of the next pile after inserting the casing to predict the bearing capacity of the pile in advance.

An object of an embodiment of the present invention is to provide a method of predicting bearing capacity of an underwater ground handling casing according to an underwater ground handling casing and a time lag effect that can predict a bearing capacity over time.

An underwater ground handling casing according to an embodiment of the present invention includes an inner casing having an inner hollow cylindrical shape; An outer casing into which the inner casing is inserted and exposes a part of the outer circumferential surface of the inner casing to the outside; And a plurality of side pressure measuring sensors attached to an outer circumferential surface of the inner casing exposed to the outside of the outer casing.

The outer casing of the underwater ground handling casing according to an embodiment of the present invention may be provided with a plurality of openings to expose a part of the outer circumferential surface of the inner casing to the outside.

The plurality of openings of the underwater ground handling casing according to an embodiment of the present invention may be spaced apart along the longitudinal direction of the outer casing.

The plurality of side pressure measurement sensors of the underwater ground handling casing according to an embodiment of the present invention may each include a strain gauge.

The inner casing of the underwater ground handling casing according to an embodiment of the present invention may be inserted into the outer casing so as to be movable relative to the outer casing.

The method of predicting bearing capacity of a submerged ground handling casing according to an embodiment of the present invention is characterized in that at the time of ground investigation, an inner casing with a plurality of lateral pressure measurement sensors attached to the outer periphery thereof and the inner casing are inserted, Providing an underwater grounding casing including an outer casing for exposing the measurement sensor to the outside; Installing the underwater ground handling casing up to a set target depth in the ground; And measuring a main surface friction force applied to the plurality of side pressure measuring sensors by relatively moving the inner casing relative to the outer casing.

The step of measuring the main surface friction force of the method for predicting the supporting force of the underwater ground handling casing according to the time lag effect according to the embodiment of the present invention may include the step of raising the inner casing with the outer casing fixed in the ground .

The measuring of the main surface friction force of the method for estimating the bearing capacity of the underwater ground handling casing according to the time lag effect according to the embodiment of the present invention may be performed after a predetermined time has elapsed after the installation of the underwater ground handling casing have.

According to the method of predicting the bearing capacity of the underwater ground handling casing according to the underwater ground handling casing and the time-lapse effect according to the embodiment of the present invention, the bearing capacity over time can be predicted.

1 is a perspective view of a submerged ground casing according to an embodiment of the present invention,
FIGS. 2 to 4 are schematic views illustrating a method for predicting bearing capacity of a submerged ground handling casing according to time-lapse effect according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventive concept. Other embodiments falling within the scope of the inventive concept may be easily suggested, but are also included within the scope of the present invention.

The same reference numerals are used to designate the same components in the same reference numerals in the drawings of the embodiments.

1 is a perspective view of an underwater grounding casing according to an embodiment of the present invention.

Referring to FIG. 1, an underwater ground handling casing 30 according to an embodiment of the present invention includes an inner casing 10 and an outer casing 20.

The outer casing 20 forms an outer appearance of the underwater ground handling casing 30 according to an embodiment of the present invention, and the inner casing 20 may have an empty cylindrical shape.

The inner casing 10 may also have an inner hollow cylindrical shape, and the outer diameter of the inner casing 10 may correspond to the inner diameter of the outer casing 20.

The inner casing 10 is inserted into the outer casing 20 while the outer circumferential surface of the inner casing 10 is inserted into contact with the inner circumferential surface of the outer casing 20.

The underwater ground handling casing 30 according to an embodiment of the present invention is connected to the buoy 300 through the cable 200. The cable 200 is connected to the inner casing 10 and the outer casing 20).

The cable 200 may be connected to the buoy 300 through a groove 13 formed in at least one of the inner casing 10 and the outer casing 20.

The buoy 300 can be provided to confirm the position where the subsequent casing 30 is inserted so that the ground survey line 100 can perform the ground survey at different positions without staying in one position .

The inner casing 10 is moved relative to the outer casing 20 to measure the frictional force after a predetermined time has elapsed after the underwater ground handling casing 30 according to the embodiment of the present invention is applied to the ground. .

This will be described later with reference to FIG. 2 and FIG.

The outer casing 20 may be provided with an opening 21 having a predetermined shape to expose a part of the outer circumferential surface of the inner casing 10 to the outside.

A plurality of openings 21 may be provided along the longitudinal direction of the outer casing 20.

A plurality of side pressure measuring sensors 11 may be spaced apart from each other on the outer circumferential surface of the inner casing 10.

The plurality of side pressure measuring sensors 11 may be mounted on a portion of the outer casing of the inner casing 10 exposed through the opening 21 of the outer casing 20. [

Accordingly, the plurality of side pressure measuring sensors 11 disposed on the outer circumferential surface of the inner casing 10 are exposed to the outside through the opening 21, and the underwater grounding casing (not shown) according to the embodiment of the present invention 30 are installed on the ground, the plurality of side pressure measurement sensors 11 come into contact with the ground surface.

The plurality of side pressure measuring sensors 11 may include strain gauges for measuring ground surface frictional forces of respective ground layers.

The strain gauges may be installed according to the order of the stratum structure, so that the surface frictional force of each stratum can be measured at one time.

FIGS. 2 to 4 are schematic views illustrating a method for predicting bearing capacity of a submerged ground handling casing according to time-lapse effect according to an embodiment of the present invention.

First, the underwater ground handling casing 30 according to an embodiment of the present invention is installed up to the set target depth in the ground.

At this time, the offshore ground survey line 100 is provided in a form in which various ground surveys such as a standard penetration test can be carried out. Depending on the conditions of the ground, the installation of the underwater ground handling casing 30 according to an embodiment of the present invention A method of indenting using a hydraulic jack can be used.

When the underwater ground handling casing 30 is installed in the ground, the ground undergoes extreme changes.

The main contents of the ground change are various such as the ground stress change and the pore pressure change, and such changes are changed again with the passage of time from the time when the underwater ground handling casing 30 is installed.

Accordingly, the supporting force of the underwater ground driving casing 30 is changed according to the elapsed time from when the underwater ground handling casing 30 is installed. Therefore, it is necessary to confirm the bearing capacity of the underwater ground handling casing 30 over time in various ground conditions.

In the method of predicting the bearing capacity of the underwater ground handling casing 30 according to the time lapse effect according to the embodiment of the present invention, the FMS based on the formula proposed by Skov and Denver (1988) The bearing force of the casing 30 can be predicted.

For example, since the change of the bearing force over time shows a tendency to be linear, the prediction of the change of the bearing force over time (for example, the set-up effect) can be expressed by the following equation have.

[Equation 1]

Figure pat00001

Here, f SO is the main surface friction at time t O , and f S is the main surface friction at time t.

Also, A means a set-up factor for each type of soil.

The bearing capacity predicting method in the underwater ground tank using a casing (30) with the passage of time effect in accordance with an embodiment of the present invention, obtain and f SO in t O using the above equation, by obtaining a f S1 from t 1 A Can be calculated.

Therefore, the value of f S at a desired time t in the future can be predicted.

That is, the value of f s at a desired time t can be predicted by measuring the surface friction with time after the underwater ground handling casing 30 is immersed in the underwater ground and maintained for a predetermined period of time.

Specifically, when the penetration of the underwater ground handling casing 30 into the underwater ground is completed, the ground survey line 100 is moved to the next drilling position, and as shown in FIG. 4, The use casing 30 is connected to the buoy 300 through the cable 200.

In this state, after the elapse of a predetermined time, the ground survey line (100) moves back to the ground and the friction force is measured by using the underwater ground handling casing (30) penetrated into the underwater ground.

The main surface friction force is measured by relatively moving the inner casing 10 relative to the outer casing 20 using a pulling device such as a hydraulic jack provided in the ground survey line 100.

At this time, the outer casing 20 is fixed in a state of being penetrated into the underwater floor, and the inner casing 10 is raised toward the sea level by the drawing device. At this time, the inner casing 10 is attached to the outer peripheral surface of the inner casing 10 And the frictional force of the main surface is measured through the plurality of side pressure measuring sensors 11.

Through the above-described embodiments, it is possible to estimate the bearing capacity over time according to the method of predicting the bearing capacity of the underwater ground handling casing according to the underwater ground handling casing and the time-lag effect according to the embodiment of the present invention.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be apparent to those skilled in the art that changes or modifications may fall within the scope of the appended claims.

10: Inner casing
11: Side pressure measurement sensor
13: Home
20: outer casing
21: opening
30: Underwater ground casing
100: Ground survey line
200: Cable
300: Buoy

Claims (8)

An inner casing having an inner hollow cylindrical shape;
An outer casing into which the inner casing is inserted and exposes a part of the outer circumferential surface of the inner casing to the outside; And
And a plurality of side pressure measurement sensors attached to an outer circumferential surface of the inner casing exposed to the outside of the outer casing.
The method according to claim 1,
Wherein the outer casing is provided with a plurality of openings to expose a part of the outer circumferential surface of the inner casing to the outside.
3. The method of claim 2,
Wherein the plurality of openings are spaced apart along the longitudinal direction of the outer casing.
The method according to claim 1,
Wherein the plurality of side pressure measuring sensors each include a strain gauge.
The method according to claim 1,
Wherein the inner casing is inserted into the outer casing so that the inner casing can move relative to the outer casing.
Providing an underwater ground handling casing including an inner casing having a plurality of side pressure measuring sensors mounted on an outer circumferential surface thereof and an outer casing having the inner casing inserted therein and exposing the plurality of side pressure measuring sensors to the outside;
Installing the underwater ground handling casing up to a set target depth in the ground; And
And measuring a main surface friction force applied to the plurality of side pressure measuring sensors by relatively moving the inner casing relative to the outer casing to predict the bearing force of the underwater ground handling casing according to the time lapse effect.
The method according to claim 6,
The step of measuring the main surface friction force includes:
Wherein the inner casing is lifted while the outer casing is fixed in the ground.
The method according to claim 6,
The step of measuring the main surface friction force includes:
A method for predicting the bearing capacity of a submerged ground casing according to the time lapse effect after a predetermined time has elapsed after the installation of the underwater ground handling casing.
KR1020140160075A 2014-11-17 2014-11-17 A casing for the soil survey of a site of the seabed and method for predicting support force of the casing with the passage of time KR20160059051A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114718107A (en) * 2022-06-10 2022-07-08 山东科技大学 Ocean suction type foundation capable of carrying out systematic negative pressure monitoring and using method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114718107A (en) * 2022-06-10 2022-07-08 山东科技大学 Ocean suction type foundation capable of carrying out systematic negative pressure monitoring and using method thereof

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