WO2020021294A1

WO2020021294A1 - Retaining engineering structure and design method for stabilizing deep excavations or earth slope instability near existing civil objects

Info

Publication number: WO2020021294A1
Application number: PCT/HR2018/000012
Authority: WO
Inventors: Zvonimir SEPAC
Original assignee: Sepac Zvonimir
Priority date: 2018-07-26
Filing date: 2018-07-26
Publication date: 2020-01-30
Also published as: HRP20230092T1; EP3827133A1; EP3827133B1

Abstract

The present invention relates to a design method for stabilizing deep excavations or earth slope instability near existing civil objects by means of a retaining engineering structure comprising a vertical building structure and a plurality of tensile batter piles (1) disposed inclining downwardly towards backfill, the vertical building structure and each of the plurality of tensile batter piles (1) are mutually coupled by a coupling means and mutually arranged at an angle β, the angle β is the angle between each of the plurality of tensile batter piles (1) and the vertical building structure at the point of their coupling by said means to the vertical. The design method comprising the steps of determining a type of the retaining engineering structure according to a deepness of excavation; determining soil condition status; determining parameters of the retaining engineering structure according to the type; carrying out retaining engineering structure construction work, wherein irrespective of the type of the retaining engineering structure a horizontal load H on the vertical building structure is calculated according the expression H = P _a - K _a x A _n x cos β where P _a is a horizontal load generated by the ground mass G ₁, K _a is coefficient of active earth pressure, and A _n is tensile force in each of the tensile batter pile (1), wherein the angle β is in a range between 15-20°. The present invention further relates to a retaining engineering structure which is suitable for carrying out said design method, the retaining engineering structure consisting of a vertical building structure and a plurality of tensile batter piles (1) disposed inclining downwardly towards backfill, the vertical building structure and each of the batter piles (1) are mutually coupled by a coupling means and are mutually arranged at an angle β to the vertical, wherein the angle β is the angle between each of the plurality of batter piles (1) and the vertical building structure at the point of their coupling by said means, the angle β is in a range between 15-20°.

Description

Retaining engineering structure and design method for stabilizing deep excavations or earth slope instability near existing civil objects

Field of the Invention

The present invention relates to a retaining engineering structure and a design method for stabilizing deep civil excavations or earth slope instability in vicinity of existing civil objects, and more particularly to the retaining engineering structure comprising a plurality of tensile batter piles and a vertical building structure for shoring excavation or earth slope instabilities in vicinity of existing civil objects.

Background Art

Development of urban regions reveals the need of excavation in vicinity to neighbor buildings more than ever. There are several methods to stabilizing excavations, such as anchorage, soil nailing, tie back, diaphragm wall, bored pile wall, braced pile wall, soldier beam and lagging and braced wall using wale struts.

Construction of structures having large design loads, such as large buildings, sites where shallow found ations have not enough bearing capacity where portions of the building are below ground level, such as parking garages, or where there are site constraints, such as property lines, that reduce the area of the excavation site, generally requires deep excavations. Such excavations may therefore have to be properly shored, which may be temporary or permanent shoring.

However, where the depth of excavations exceeds certain values; deflection tolerances are stringent due to proximate structures or utilities; or where the soil is soft or lacks cohesion, the soldier pile and lagging systems may need to be reinforced with tie-backs, struts, or internal bracing. Such reinforcement techniques, however, increase costs, are laborious, and are prone to interfere with proximate structures, such as where tieback anchors may cross property lines, roadways, and/or buried utilities, for example.

Old traffic routes are for the most part in such a condition that they no longer have any significant stability reserves in their original geometry and in their current stress. The widening of lanes on slopes requires the protection of terrain jumps, as in incisions and embankments, unless a safe stand demolition is not possible. These terrain jumps are secured by retaining walls that are subject to earth pressure and must withstand this.

Especially in steep and slip-prone terrain, there is a risk that instability of the traffic route to be widened or securing the existing buildings will be caused by the construction of the excavation pit or that landslides will be triggered which cause great damage to humans and the environment.

In order to prevent this, costly safety measures, such as anchorages and others, often have to be taken.

In the field of foundation engineering, due to changes in stress - strain relations in the soil, caused by deep excavations or soil condition changes in earth slopes, the initial static equilibrium changes, causing instability. The consequence of instability is the breakdown of all coupled natural and artificial space with material damage, which generally exceeds the value of the influenced space. Engineering response to these events is a stable retaining engineering str cture. In accordance with the present invention, the retaining engineering structure is projected based on the newly-predicted static equilibrium that is associated with the predetermined Fs stability factor.

The present invention provides one more purposeful a retaining engineering structure for all horizontal loadings in the field of low building constructions. The starting point is the desire that the significant problems present in the engineering approach of the present retaining engineering structure are brought in at least the same level as other building constructions.

The idea of a new retaining engineering structure and a design method is in analogous to the construction of one historical construction, the arch, which stabilizes the vertical loading by its horizontal effect. Here, instead of the arch, a complex pilot system will be used, which will shift the horizontal loading to a greater extent in the vertical effect of the pilot system.

It is the object of the present invention to propose a retaining engineering structure and a design method of the type defined in the introduction, which consists of simple components and compared to conventional devices or method execution cost-effective, simple and above all safe to create. This is to exclude disadvantages of the conventional method by eliminating stability-reducing interventions in the soil, as they occur in the excavations or earth slope instability.

Accordingly, the object of the present invention is to provide a retaining engineering structure designed and calculated by a new method that achieves 20-25% savings in realizing final construction work.

The present invention provides the retaining engineering structure and the method for three basic cases, which differ in technological execution possibilities more than in design method, namely for:

- deeper excavations, larger than 8 m;

- excavations up to 8 m; and

- natural slope instability near existing civil objects.

In accordance with the present invention, stability of excavations up to 8 m and natural slope instability near existing civil objects is achieved by the retaining engineering structure comprising a plurality of coupled tensile and pressure piles, while stability of deeper excavations larger than 8 m is achieved by the retaining engineering structure comprising a coupled tensile piles and a vertical building structure such as a reinforced concrete (RC) pile wall or a reinforced concrete (RC) diaphragm wall. Tensile piles are inclined, while pressure piles are vertically oriented.

This object is achieved by the defined in the characterizing part of the independent claim 1 design method for stabilizing deep civil excavations or earth slope instability in vicinity of existing civil objects, as well as in the characterizing part of claim 1 1 defining a retaining engineering structure.

Brief summary of the invention

The present invention relates to a retaining engineering structure and a design method for stabilizing deep civil excavations or earth slope instability in vicinity of existing civil objects, and more particularly to the retaining engineering structure comprising a plurality of tensile batter piles and a vertical building structure for shoring excavation or earth slope instabilities in vicinity of existing civil objects. The design method in accordance with the present invention by means of a retaining engineering structure comprising a vertical building structure and a plurality of tensile batter piles disposed inclining downwardly towards backfill, the vertical building structure and each of the plurality of tensile batter piles are mutually coupled by a coupling means and mutually arranged at an angle b, the angle b is the angle between each of the plurality of tensile batter piles and the vertical building structure at the point of their coupling by said means to the vertical, the design method comprising the steps of determining a type of the retaining engineering structure according to a deepness of axcavation; determining soil condition status; determining parameters of the retaining engineering structure according to the type; and carrying out retaining engineering structure construction work, wherein irrespective of the type of the retaining engineering structure a horizontal load Won the vertical building structura is calculated according the expression

H - P_a— K_a x A_n x cos b

where P_a is a horizontal load generated by the ground mass Gu K_a is coefficient of active earth pressure, and A_n is tensile force in each of the tensile batter pile, wherein the angle b is in a range between 15-20°.

The retaining engineering structure in accordance with the present invention comprises three mutually coupled structural elements, namely a plurality of tensile batter piles, a vertical building structure, the vertical building structure may be a plurality of vertical pressure soldier piles, RC diaphragm wall or a RC soldier pile wall, and a coupling means for coupling said batter piles and the vertical building structure, wherein the plurality of tensile batter piles are disposed inclining downwardly towards backfill at an angle b in a range between 15° to 20° to the vertical, where the coupling means may be a tube anchorage or a RC head connection beam. The angle b is the angle to the vertical between the plurality of tensile batter piles and the vertical building structure at the site of their mutual coupling by the coupling means.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present invention will be explained In more detail below on the basis of three exemplary embodiments taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic isometric drawing of a retaining engineering structure for use in deeper excavations according to the present invention;

FIG. 2 is a cross sectional view of an inclined pile arranged in a RC pile wall or RC diaphragm wall according to one embodiment of the present invention;

FIG. 3 is a side view of a retaining engineering structure for use in deeper excavations, pressure distribution on a RC pile wall or RC diaphragm wall, and a diagram showing the forces;

FIG. 4 is a schematic isometric drawing of a retaining engineering structure for use in excavations up to 8 m according to the present invention;

FIG. 5 is a cross sectional view of an inclined batter pile and a vertical pile coupled to a RC head connection beam;

FIG. 6 is a side view of a retaining engineering structure for use in excavations up to 8 m, pressure distribution on a vertical pile, and a diagram showing the forces;

FIG. 7 is a schematic isometric drawing of a retaining engineering structure for use in earth slope instability near existing civil objects according to the present invention; and

FIG. 8 is a side view of a retaining engineering structure for use in in earth slope instability near existing civil objects, pressure distribution on a vertical pile, and a diagram showing the forces.

DETAILED DESCRIPTION OF THE PREFERED EMODIMENTS

The following detailed description is directed toward systems and design methods for use in connection with earth retention walls of deep excavations, excavations up to 8 m, and for stabilizing earth slope instability near existing civil objects.

Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise" and variations thereof, such as,“comprises” and "comprising” are to be construed in an open, inclusive sense, that is, as“including, but not limited to."

As used in this specification and the appended claims, the singular forms“a,”“an,” and“the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term“or" is generally employed in its sense including“and/or" unless the content clearly dictates otherwise. The term "soldier piles or soldier pile wall”, as used in the present patent application and patent claims, are retaining walls with reinforced concrete piles spaced at regular intervals.

The term“tensile batter piles”, as used in the present patent application and patent claims, are piles arranged at an angle b with the vertical to resist a lateral force spaced at regular intervals, the angle b is to the vertical between a plurality of tensile batter piles and a vertical building structure at the site of their mutual coupling by a coupling means.

The implementations, geometrical configurations, materials mentioned and/or dimensions shown in the figures are optional and given for the purposes of exemplification only.

Moreover, although the method may be used for forming a "cementitious" retaining wall, for example, it may be used to form retaining walls, or other wall-types, made from other flowable materials. For this reason, the use of expressions such as "cementitious", "concrete", etc., as used herein should not be taken as to limit the scope of the method to these specific materials and includes all other kinds of materials, objects and/or purposes with which the method could be used and may be useful. Furthermore, the term

"cementitious" refers to such substances as concrete and other stiffening flowable materials. Alternatively, different non-flowable materials can be used for forming the retaining wall,

The system of complex pilots, with the greater part of the horizontal loading, converts to the vertical effect of the pilot, resulting in double benefit. Reduction of horizontal loading on the vertical building structure and use of a large supporting vertical bearing capacity without any harmful consequences for the system of complex pilots.

In accordance with the present invention, a retaining engineering structure comprises three mutually coupled structural elements, namely a plurality of tensile batter piles, a vertical building structure, the vertical building structure may be a plurality of vertical pressure soldier piles, RC diaphragm wall or a RC soldier pile wall, and a coupling means for coupling said batter piles and the vertical building structure, wherein the plurality of tensile batter piles are disposed inclining downwardly towards backfill at an angle b in a range between 15° to 20° to the vertical, where the coupling means may be a tube anchorage or a RC head connection beam. The angle b is the angle to the vertical between the plurality of tensile batter piles and the vertical building structure at the site of their mutual coupling by the coupling means. The site of their mutual coupling is arranged at upper portion of the vertical building structure or at the top of the vertical building structure.

Fig. 1 illustrate an example embodiment of the retaining engineering structure for shoring of deeper excavations, fig. 4 illustrate an example embodiment of Ihe retaining engineering structure for shoring of excavations up to 8 m, and fig. 7 illustrate an example embodiment of the retaining engineering structure for shoring of natural slope instability near existing civil objects.

Referring to fig. 1, the retaining engineering structure comprises the plurality of tensile batter piles 1, disposed inclining downwardly towards backfill at the angle b to the vertical, connected to the vertical building structure, namely lo the RC diaphragm wall 2. In another embodiment of the present invention, for shoring deeper excavations the vertical building structure may be the RC soldier pile wall 5. The RC diaphragm wall 2 is a reinforced concrete structure constructed in-situ by known techniques. The RC diaphragm wall 2 comprises reinforcement in the form of a steel cage 10. Each tensile batter pile 1 is carried out by jet grouting installation or CFA (continues fly auger) piling technology. Each tensile batter pile 1 is provided with a reinforcing steel bar 8 extending centrally along the tensile batter pile 1. The reinforcing steel bar 8 extends along a length L_g of the batter pile 1 and further to reach a vertical front face 15 of the RC diaphragm wall 2 and beyond said vertical front face 15 for a length enabling coupling of the each of the tensile batter piles 1 with the RC

diaphragm wall 2 by means of a tensioning means. Referring to fig. 3, the tensile batter pile 1 has total length , and the reinforcing steel bar 8 is further extending from concrete part of the tensile batter pile 1 for a length Each of the tensile batter piles 1 are placed at the angle li in the range between 15“ to 20“ to the vertical, where the angle b is the angle to the vertical between the plurality of tensile batter piles 1 and the RC diaphragm wall 2 at the site of their mutual coupling by a coupling means. As seen in fig. 2, each of the tensile batter piles 1 is coupled to the RC diaphragm wall 2 by means of the tensioning means such as a nut 11, a transient supporting element 12 and an anchor plate 13 (or a flange brace). The anchor plate 13 may be made from steel, or other high strength material, and is firmly fixed to the vertical front face 15 in vicinity of an upper part of the RC diaphragm wall 2, The anchor plate 13 is provided with a trough-hole sized and shaped enabling passing therethrough of the reinforcing steel bar 8, and fixing and pre-stressing the batter piles (1) and the reinforcing steel bar 8 by the means of the nut 11 and the transient supporting element 12. The RC diaphragm wall 2 comprises a plurality of parallelly aligned tubular members 14 through which undergoes each reinforcing steel bar 8 of the tensile batter piles 1. Each tubular member 14 undergoes the RC diaphragm wall 2 at a distance e, the distance e is distance measured from a top of the RC diaphragm wall 2, and each tubular member 14 is disposed inclining downwardly towards backfill at the angle b to the vertical. The tubular members 14 may be made from steel, or other high strength material, The tubular members 14 are inserted into the RC diapraghm wall 2 before pouring cement. The tensile batter piles 1 are pre-stressed in a range between 25-35% of a batter pile tensile bearing capacity.

Referring to figures 4 to 6 illustrating an example embodiment of the retaining engineering structure for shoring of excavations up to 8 m, the retaining engineering structure comprises the plurality of tensile batter piles 1, disposed inclining downwardly towards backfill at the angle b to the vertical, connected to the vertical building structure, the vertical building structure is the RC soldier pile wall 5. The RC soldier pile wall 5 is a reinforced concrete structure constructed in-situ by known techniques. The RC soldier pile wall 5 comprises reinforcement in the form of the steel cage 10. Each tensile batter pile 1 is earned out by jet grouting installation or CFA (continues fly auger) piling technology. Each tensile batter pile 1 is provided with a reinforcing steel profile 9 extending centrally along the tensile batter pile 1. Referring to fig. 6, the tensile batter pile 1 has total length Li, and the RC soldier pile wall 5 has total length 4. Each of the tensile batter piles 1 are placed at the angle b in the range between 15° to 20° to the vertical, where the angle is the angle to the vertical between the plurality of tensile batter piles 1 and the RC soldier pile wall 5 at the site of their mutual coupling by a coupling means. As seen in fig. 5, each of the tensile batter piles 1 is coupled at a

lop of the RC soldier pile wall 5 by means of a RC head conneclion beam 4. The RC head connection beam 4 is a reinforced concrete structure comprising a reinforced gasket 7, constructed in-situ by known techniques.

Referring to figures 7 and 8 illustrating an example embodiment of the retaining engineering structure for an example embodiment of the retaining engineering structure for shoring of natural slope instability near existing civil objects, the retaining engineering structure comprises the plurality of tensile batter piles 1 , disposed inclining downwardly towards backfill at the angle b to the vertical, connected to the vertical building structure, the vertical building structure is a plurality of soldier piles 6. The soldier piles 6 are a reinforced concrete structure constructed in-situ by known techniques. The coupling means such as the RC head beam 4 for coupling the tensile batter piles 1 and the soldier piles 6 is mounted on the top of the vertical building structure. The tensile batter piles 1 are arranged at an angle S in the range of 15° - 20°. Each tensile batter pile 1 is carried out by jet grouting installation or CFA (continues fly auger) piling technology. Referring to fig. 8, the tensile batter pile 1 has total length U, and the soldier piles 6 have total length U. Each of the tensile batter piles 1 is disposed inclining downwardly towards backfill at the angle b in the range between 15° to 20° to the vertical, where the angle b is the angle to the vertical between the plurality of tensile batter piles 1 and the soldier piles 6 at the site of their mutual coupling by a coupling means. As seen in fig. 7, each of the tensile batter piles 1 and each of the soldier pile 6 are coupled at a top by means of the RC head connection beam 4. The RC head connection beam 4 is a reinforced concrete structure comprising a reinforced gasket 7, constructed in-situ by known techniques.

A design method for stabilizing deep excavations or earth slope instability near existing civil objects by means of a retaining engineering structure consisting of a vertical building structure and a plurality of tensile batter piles 1, the vertical building structure and each of the tensile batter piles 1 are mutually coupled by a coupling means and mutually arranged at an angle b, the angle b is the angle to the vertical between each of the tensile batter piles 1 and the vertical building structure at the point of their coupling by said means, the design method comprising the following steps:

a) determining a type of the retaining engineering structure according to a deepness of excavation; b) determining soil condition status;

c) determining parameters of the retaining engineering structure according to the type; and

d] carrying out retaining engineering structure construction work.

Irrespective of the type of the retaining engineering structure a horizontal load H on the vertical building structure is calculated according the expression

H=P_a— K_a x A_n x cos b

where P_a is a horizontal load generated by the ground mass G/, K_a is coefficient of active earth pressure, and A_n is tensile force in each of the tensile batter pile (1), wherein the angle b is in a range between 15- 20°.

A basic principle of the design method for stabilizing deep excavation or earth slope instabilities near civil objects in steep and sloping terrain is considered as three masses of natural soil, namely - active or loading ground mass G/ at excavation facilities or sliding mass at earth slope instability;

- exhumed soil ground mass G; at excavation facilities or conditional deflating part of slope in earth slope instability;

- the base or anchoring mass of the soil Gj at the excavation facilities or earth slope instability case; and

- the sloping layer mass G4 in the case of earth slope instability.

The horizontal effect of mass G1 as a result of excavation of soil or soil sliding is a horizontal load P₃ as active earth pressure

Pi— GixK_j [1]

wherein G) is a ground mass and Kg is coefficient of active earth pressure.

The plurality of tensile batter piles arranged at the angle b in the range between 15° to 20° with its tensile force A_n reduces the loading of the ground mass G1 by transferring it to the vertical force of a vertical building structure, the vertical building structure may be a RC soldier pile wall 5, a RC diaphragm wall 2 or a soldier pile 6.

Therefore, irrespective of the type of the retaining engineering structure the horizontal load on the vertical building structure, with reference to which the following expression is established:

P_a— K_a X A_n x cos b [2]

For deeper excavations, as illustrated in fig. 1 , the retaining engineering structure comprises the plurality of tensile batter piles 1 and the RC diaphragm wall 2 are mutually connected by the plurality of parallelly aligned tubular members 14 as illustrated in fig. 2, the following equilibrium equations expressing forces per unit linear meter length in the elements of the retaining engineering structure are established:

wherein A'_n is tensile force in each of the tensile batter pile 1, b is span of reaction forces of the vertical building structure and span of a catenary part of the batter piles 1, J?J,is pressure force in the vertical building structure, and B_t’ is transversal force in the vertical building structure.

For excavations up to 8 m and earth slope instability near existing civil objects, as illustrated in fig. 4 and respectively fig. 7, the retaining engineering structure comprises the plurality of tensile batter piles 1 and the plurality of soldier piles 6 mutually connected by a RC head connection beam 4, the following equilibrium equations expressing forces per unit linear meter length in the elements of the retaining engineering structure are established:

3 Xjj^xcos fixh \ xtan b

M_A' =

32 xb [6]

wherein A_n' is tensile force in each of the tensile batter pile 1, b is span of reaction forces of vertical building structure, B„is pressure force in the vertical building structure, and B'_t is transversal force in the vertical building structure. A'_t is transversal force in each of the batter pile 1, M_A' is moment force in a point

A of the batter pile 1 ,

is a retained height (depth of soil excavation) and h₂ is an embedment depth of the tensile batter piles 1 and pressure piles 5 in the soil, K_a is koeficient of active earth pressure. The point A is the intersection point between the retained height h_t and embedment depth h₂.

EXAMPLE 1

Technical solution of stability by means of the coupling of the tensile batter pile and the RC soldier pile wall or the RC diaphragm wall for deeper excavations, larger than 8 m.

The excavation is earned out for depths greater than 8 m, which means that in most cases it is necessary to ensure, in addition to static and hydraulic stability.

Based on the above mentioned, the RC soldier pile wall 5 or RC diaphragm wall 2 are designed as watertight.

The RC diaphragm wall 2 is earned out with the usual technology of thickness of d=40 to 80 cm and depths of 12 to 24 m. The coupling means such as the tubular member 14 for interconnecting each of the tensile batter pile 1 and the RC diaphragm wall 2 is mounted. The tubular anchorages 14 may be made from steel, or other high strength material.

Each of the tensile batter pile 1 is arranged at an angle b in the range of 15° - 20^a using jet grouting installation or CFA pile technology. The reinforcing steel bar 8 having surface area As, with 3 m of free base for the prestressing needs, is installed throughout the length of each of the batter pile 1. Each batter pile 1 is prestressed in the range between 25-35% of the tensile strength of the tensile batter pile 1.

Tensile batter pile 1

L_t is length of the tensile batter piles 1, b is span of reaction forces of the vertical building structure and span of a catenary part of the batter piles 1 (see figure 3), d is diameter of the tensile batter piles 1, dj = 1.5 - 3.0 m is spacing of the tensile batter piles 1 center to center.

The reinforcing steel bar 8 has surface area A_s = 10 - 25 cm².

kN

Modulus of elasticity of the reinforcing steel bar 8 E. = 21000— strength of the reinforcing steel bar cmr

8 o_s = 800 - 1200

Axial tensile bearing capacity A_{n q Rd} of the tensile baiter pile 1 regarding soil is calculated according following equation:

wherein a_q is earth pressure, <p_d is angle of internal friction, and y_B is partial safety coefficient, and (L_t— b ) is an anchoring part of each tensile batter pile 1.

Axial bearing capacity N_{s Rd} of the tensile batter pile 1 regarding the reinforcing steel bar is calculated according following equation:

where y_s is partial safety coefficient.

RC pile wall 5 or RC diaphragm wall 2 - vertical building structure

bis length of the RC pile wall 5 or the RC diaphragm wall 2, d = 40 - 80 cm is thickness of the RC pile wall 5 or the RC diaphragm wall 2.

Vertical bearing capacity B_{n q Rd} of the RC pile wall 5 or RC diaphragm wall 2 at the point B (see figure 3), the point B is point at the RC pile wall 5 or RC diaphragm wall 2 base, is calculated according following equation:

B_n,_qJtd = [ + h₂) x Y' x N_q x A_b [13]

Where h is the retained height and h₂ is an embedment depth of the vertical building structure, g is weight of soil, N_q is coefficient of soil bearing capacity, A_b is base area of vertical bearing structure. Horizontal bearing capacity B_{t q Rd} of the vertical building structure at the point B (see figure 3) is calculated according following equation:

Bt,q,Rd = Pp X d₂ + B’_n x tan f_ά [14]

where P_p is passive soil resistance, B_n' is pressure force in the vertical building structure, <p_d angle of internal soil friction.

Proof of the stability of the retaining engineering structure

To prove the stability of the retaining engineering structure, the following conditions have to be satisfied:

A'_n d x F_s < A_{n q Rd} [15]

B'_t d₂ x F_$ < B_{t q Rd} [16]

B_n’ d₂ x F_s < B_{n q Rd} [17] where A_{n q>Rd} is axial bearing capacity of batter pile regarding soil, B_{n q Rd} is axial bearing capacity of vertical building structure regarding soil, B_{t q Rd} is transversal bearing capacity of vertical building structure regarding soil, F_s is factor of stability.

EXAMPLE 2

Technical solution of stability by means of the coupling of the tensile batter pile and the soldier pile wall for excavations up to 8 m

The excavation is earned out for depths up to 8 m, which means that in most cases it is necessary to ensure, in addition to static and hydraulic stability.

Based on the above mentioned, the RC soldier pile wall 5 is designed as watertight.

The RC soldier pile wall 5 is carried out with the usual technology with diameter of each pile 40 to 60 cm and depths of 8 to 12 m. The coupling means such as the RC head beam 4 tor connecting the tensile batter piles 1 and the RC soldier pile wall 5 is mounted on the top of the vertical building structure.

The tensile batter piles 1 are arranged at an angle b in the range of 15° - 20 ^e using jet grouting installation or CFA pile technology. The reinforcing steel profile 9 is an IPE profile, having surface area As.

Tensile batter pile 1

LI is length of the tensile batter piles 1, d is diameter of the tensile batter piles 1; di = 1.5 - 3.0 m is spacing of the tensile batter piles 1 center to center.

The reinforcing steel profile 9 is IPE profile having surface area A_s = 30 - 40 cm²,

fcJV

Modulus of elasticity of the reinforcing steel profile 9 is E_s = 21000— , strength of the reinforcing steel profile 9 is a_s = 300— 400

Axial tensile bearing capacity A_{n q Rd} of the tensile batter pile 1 regarding soil is calculated according following equation:

_ <r_qxtan<p,ixdxii

ln,q,Rd X Li [18]

YR

wherein a_q is earth pressure, <p_d is angle of internal friction, and

is partial safety coefficient. Axial bearing capacity N_{s Rd} of the tensile batter pile 1 regarding the reinforcing steel profile 9 is calculated according following equation:

where y_s is partial safety coefficient. Horizontal bearing capacity A_{t q Rd} of the tensile batter pile 1 at the point A regarding soil (see figure 6) is calculated according following equation:

Where g' is weight of soil, h₀ is height of retained soil and h₂ is an embedment depth of the batter pile 1, K_v is coefficient of passive earth pressure, d is diameter of batter pile, y_R is partial safety coefficient. RC soldier pile wall 5

L2 is length of RC soldier pile wall 5, d = 40 - 60 cm is diameter of the RC soldier pile wall 5.

Vertical bearing capacity B_{n q Rd} of the RC soldier pile wall 5 at the point B (see figure 6) is calculated according following equation:

is the retained height and h₂ is the embedment depth of the vertical building structure, namely RC soldier pile wall 5, g’ is weight of soil, N_q is koeficient of soil bearing capacity, A_b is base area ol the vertical bearing structure.

Horizontal bearing capacity B_{t q Rd} of the vertical building structure at the point B (see figure 6) is calculated according following equation:

where P_p is passive soil resistance, B_n’ is pressure force in the RC soldier pile wall, f_L angle of internal soil friction.

Proof of stability

To prove stability of the retaining engineering structure, the following conditions have to be satisfied:

A_T' i di x F_s < A_{n q Rd} [23]

B d₂ F_s < B_{[ q Rd} [24]

B_n' d₂ x F_s < B_{n q Rd} [25]

A_c d_t x F_s < A_{t q Rd} [26] where A_{n q Rd} is axial bearing capacity of the tensile batter pile 1 regarding soil, B_{n>Q Rd} is axial bearing capacity of the RC soldier pile wall 5 regarding soil, B_{t q Rd} is transversal bearing capacity of the RC soldier pile wall 5 regarding soil, A_{t q Rd} is transversal bearing capacity of the tensile batter pile 1 regarding soil.

EXAMPLE 3

Technical solution of stability by means of the coupling of the tensile batter pile and the soldier pile for earth slope instability

When there is recorded evidence of soil subsidence, the slope is in balance with residual strength parameters (p_res and c_res. This incurred state is defined by the "signal matching” system, where the model is physically created, and the parameters that support this model are read from the already created model and serve as the basis for a project design solution for stability.

Stability of the system is ensured by the provision of sufficient reaction forces R_con , in the plain of sliding surface so that R_con > 0, 5 x fi_SOff _rei, after which the system with the shear strength in the plane of slipping R_{I0ii rej} + R_con is solved as Rankine's half-balance state of equilibrium.

The required reaction force is calculated according following equation:

Where ho is depth of sliding layer, and Uio_pe is length of sliding plane.

For the stability of the system the reaction force R_con in the plain of sliding surface must be such that following condition is satisfied: yl/+ £t₍ > ft₍on

Technical solution of stability by means of the coupling of the tensile batter piles 1 and the soldier piles 6. The soldier piles 6 are carried out with the usual technology. The coupling means such as RC head beam 4 for coupling the tensile batter piles 1 and the soldier piles 6 is mounted at the top of the vertical building structure. The tensile batter piles 1 are arranged at an angle b in the range of 15° - 20" using jet grouting installation or CFA pile technology. The reinforcing steel profile 9 having surface area A_s.

Tensile batter pile 1

Li is length of the tensile batter piles 1, d is diameter of the tensile batter piles 1 d=40-60 cm, spacing of the tensile batter piles center to center di = 1.5 - 3.0 m.

The reinforcing steel profile 9 I PE profile has surface area A_s = 30 -40 cm²,

kN

Modulus of elasticity of the reinforcing steel profile 9 £’, = 21000— strength of the reinforcing steel

cm*

profile 9 a_s = 300 - 400

Axial tensile bearing capacity A_{n q id} of the tensile batter pile 1 regarding soil is calculated according following equation:

wherein a_q is earth pressure, f_ά is angle of internal friction, and y_R is partial safety coefficient.

Axial bearing capacity N_{s Rd} of the tensile batter pile 1 regarding the reinforcing steel profile 9 is calculated according following equation:

where y_s is partial safety coefficient.

Horizontal bearing capacity A_{t q Rd} of the batter pile at the point A (see figure 8) is calculated according following equation:

where y' is weight of soil, h₀ is the depth of the loading soil layer and h₂ is the embedment depth of the vertical building structure, namely of the tensile batter piles 1, K_p is coefficient of passive earth pressure, d is diameter of the tensile batter pile 1, y_fl is partial safety coefficient, the point A is the intersection point between the retained height hi and embedment depth /¾.

Soldier pile 6

Lj is length of the soldier piles 6, diameter of each soldier pile 6 cf = 40 - 80 cm.

Vertical bearing capacity B_{n q Rd} of the soldier pile at the point B (see figure 8), the point B is point at soldier pile 6 base is calculated according following equation:

Where h_t is retained height and h₂ is embedment depth of the vertical building structure , y' is weight of soil, N_q is koeficient of soil bearing capacity A_b is base area of the vertical bearing structure.

Horizontal bearing capacity B_{t q Rd} of the vertical building structure at the point B (see figure 8) is calculated according following equation:

B_{t q Rd} = P_p x d₂ + B_n' x tan <p_d [32] where P_p is passive soil resistance, B_n‘ is pressure force in the vertical building structure, namely the soldier pile 6, <p_d is angle of internal soil friction.

A' d_t x F_s < A_{n q Rd} [33] B'_t d₂ x Fs < B_{t q d} [34]

Bn' d₂ x F_s < B_{n q Rd} [35]

A’_t d₂ x Fs < A_{t q Rd} [36]

A^r _t+ B_t' > R_con [37]

where A_{ni(Ji Rd} is axial bearing capacity of each tensile batter pile 1 regarding soil, B_{n q Rd} is axial bearing capacity of the vertical building structure, namely each soldier pile 6 regarding soil, B_{t q Rd} is transversal bearing capacity of the vertical building structure, namely each soldier pile 6 regarding soil, A_{[ q Rd} is transversal bearing capacity of each tensile batter pile 1 regarding soil. Numerous characteristics and advantages of the invention have been set forth in the foregoing description, together with details of the structure and function of the invention, and the novel features thereof are pointed out in the appended claims, The disclosure, however, is illustrative only and changes may be made in detail, especially in matters of shape, size and arrangement of parts, within the principal of the invention, to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. A design method for stabilizing deep excavations or earth slope instability near existing civil objects by means of a retaining engineering structure comprising a vertical building structure and a plurality of tensile batter piles (1) disposed inclining downwardly towards backfill, the vertical building structure and each of the plurality of tensile batter piles (1) are mutually coupled by a coupling means and mutually arranged at an angle b , the angle b is the angle between each of the plurality of tensile batter piles (1) and the vertical building structure at the point of their coupling by said means to the vertical, the design method comprising the following steps:

a) determining a type of the retaining engineering structure according to a deepness of excavation;

b) determining soil condition status;

c) determining parameters of the retaining engineering structure according to the type; and d) carrying out retaining engineering structure construction work,

characterized by that

H = P_a - K_a x A_n x cos b

where P_a is a horizontal load generated by the ground mass Gj, K_a is coefficient of active earth pressure, and A_n is tensile force in each of the tensile batter pile (1), wherein the angle b is in a range between 15-20°.

2. The design method according to claim 1 , wherein for excavations larger than 8 carrying out the vertical building structure as a RC pile soldier wall (5) or a RC diaphragm wall (2).

3. The design method according to claim 1, wherein for excavations up to 8 m and earth slope instability near existing civil objects carrying out the vertical building structure as a plurality of soldier piles (6) or a RC pile soldier wall (5).

4. The design method according to claims 1 and 2, wherein the following equilibrium equations expressing forces per unit linear meter length in the elements of the retaining engineering structure are established:

b x tan b x A_n' x cos b

B_n' xb tan b— -ax (P_a - K_a x A_n' x cos b) = O

wherein A'_n is tensile force in each of the tensile batter pile (1), b is span of reaction forces of the vertical building structure and span of a catenary part of the batter piles (1), B_n' is pressure force in the vertical building structure at its base, and B_t' is transversal force of the vertical building structure at its base.

5. The design method according to claim 4, wherein the tensile batter piles (1) are pre-stressed in a range between 25-35% of a batter pile tensile bearing capacity.

6. The design method according to claims 1 and 3, wherein the following equilibrium equations expressing forces per unit linear meter length in the elements of the retaining engineering structure are established:

h\ x ίahb X A'„ XCOs 2h_z +y , fti

B_n' X bx tan b— xs;-yX(P.-ff.x/>ixc._S/!) ₊ Mi = o

2xb 3

wherein A_n' is tensile force in each of the tensile batter pile (1), b is span of reaction forces of each soldier pile (6) or the RC soldier pile wall (5), if^is pressure force in each soldier pile (6) or the RC soldier pile wall (5) at base, and B'_t is transversal force in each soldier pile (6) or the RC soldier pile wall (5) at base, A'_t is transversal force in each of the tensile batter pile (1), M_A' is moment force in point A of each of the tensile batter pile (1), the point A is the intersection point between a retained height hi and an embedment depth h_2,

7. The design method according to claims 1, 2, 4 and 5, wherein the following conditions have to be satisfied;

B'_t d₂ x F_s < B_{t q Rd}

B_n' d₂ x F_s < B_{n q Rd} where A„_{q Rd} is axial bearing capacity of each of the tensile batter pile (1) regarding soil, B_{n q Rd} is axial bearing capacity of the vertical building structure regarding soil, B_{t q Rd} is transversal bearing capacity of the vertical building structure regarding soil, F_s is factor of stability, the Fs is in a range between 1,2 to 1,5.

8. The design method according to claims 1, 3 and 5, wherein for excavations up to 8 m the following conditions have to be satisfied:

A_t' i d₂ x F_s < A_{n q Rd}

A'_t d₁ x F_s < A_{t q>Rd}

B'_t d₂ x F_s < B_{tA lRd}

B_n' d₂ x F_s < B_{n q R} where A_{n q Rd} is axial bearing capacity of each tensile batter pile (1) regarding soil, B_{n q Rd} is axial bearing capacity of each soldier pile (6) or the RC soldier pile wall (5) at base regarding soil, B_{t q Rd} is transversal bearing capacity of each soldier pile (6) or the RC soldier pile wall (5) at base regarding soil, A_{t q Rd} is transferzal force in each of the tensile batter pile (1) regarding soil, F_s is factor of stability, the Fs is in a range between 1 ,2 to 1,5.

9. The design method according to claims 1, 3 and 6, wherein for earth slope instability near existing civil objects the following conditions have to be satisfied: tail <p_res) X I^slope

A't d_t x F_s < A_{t q Rd}

B_n d-2 X Fg < Bn,q,Rd

B't d₂ X Fs < B t,q, Rd

where A_{n q Rd} is axial bearing capacity of each of the tensile batter pile regarding soil, B_{n q Rd} is axial bearing capacity of each soldier pile (6) at its base regarding soil, B_{t q Rd} is transversal bearing capacity of each soldier pile (6) at its base regarding soil, A_{t q Rd} is transferzal force in each of the tensile batter pile (1) regarding soil , F_s is factor of stability, (p_Tes and c_res are residual strength soil parameters, R_cmi is reaction shear strength of the retaining engineering structure, R_sou,res '^s residual shear strength of soil, y'is weight of soil, h₀ is depth of a sliding soil layer, L_slope is length of a failure plane.

10. The design method according to any of preceding claims, wherein the step of canying out retaining engineering structure construction work comprises the steps of:

i. installation of the tensile batter piles (1) at the angle b in the range between 15-20°, ii. installation of the vertical building structure, and

iii. coupling of each of the tensile batter pile (1) to the vertical building structure by means of the coupling means,

wherein the vertical building structure is carried out as the RC pile soldier wall (5), RC diaphragm wall (2), or the soldier piles (6), where each of the tensile butter piles (1) are earned out by a jet grouting installation or by CFA piling technology, and the soldier piles (6) is earned out by CFA piling technology.

11. A retaining engineering structure which is suitable for canying out a design method according to one or more of claims 1 - 10. the retaining engineering structure consisting of a vertical building structure

and a plurality of tensile batter piles (1) disposed inclining downwardly towards backfill, the vertical building structure and each of the batter piles (1) are mutually coupled by a coupling means and are mutually arranged at an angle b to the vertical, characterized by that the angle b is the angle between each of the plurality of batter piles (1) and the vertical building structure at the point of their coupling by said means, the angle b is in a range between 15-20°.

12. The retaining engineering structure according to claim 11 , wherein the vertical building structure is a RC diaphragm wall (2).

13. The retaining engineering structure according to claim 11, wherein the vertical building structure is a RC pile soldier wall (5).

14. The retaining engineering structure according to claims 11 - 13, wherein the coupling means is a plurality of parallelly aligned tubular members (14), each tubular member (14) undergoes in vicinity of an upper part of the RC pile soldier wall (5) or the RC diaphragm wall (2), and each is disposed inclining downwardly towards backfill at the angle IΪ to the vertical.

15. The retaining engineering structure according to claims 11-14, wherein through center of each of the batter piles (1) undergoes a reinforcing steel bar (8), where the tensile batter pile (1) has total length

Lg, and the reinforcing steel bar (8) is further extending from concrete part of the tensile batter pile

(1) for a length Lo.

16. The retaining engineering structure according to claims 1 1-15, wherein each of the batter pile (1) is connected to the RC pile soldier wall (5) or the RC diaphragm wall (2) by means of the reinforcing steel bar (8), a nut (11) and an anchor plate (13), the anchor plate (13) is provided with a trough-hole enabling each reinforcing steel bar (8) to undergo the anchor plate (13), where the anchor plate (13) is firmly fixed to a vertical front face (15) of the RC pile soldier wall (5) or of the RC diaphragm wall

(2)·

17. The retaining engineering structure according to claim 11, wherein the vertical building structure is a plurality of vertical pressure soldier piles (6).

18. The retaining engineering structure according to claims 13 and 17, wherein through center of each of the batter piles (1) undergoes a reinforcing steel profile (9).

19. The retaining engineering structure according to claims 11, 13 and 17, wherein the coupling means is a RC head connection beam (4).

20. The retaining engineering structure according to claim 7 and 8, wherein the RC head connection beam (4) comprises a reinforcement basket (7).