CN112115599A - Method for calculating hole spacing of weakened top plate of intensive drilling - Google Patents

Method for calculating hole spacing of weakened top plate of intensive drilling Download PDF

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CN112115599A
CN112115599A CN202010945806.3A CN202010945806A CN112115599A CN 112115599 A CN112115599 A CN 112115599A CN 202010945806 A CN202010945806 A CN 202010945806A CN 112115599 A CN112115599 A CN 112115599A
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borehole
rock mass
mass around
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stress
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CN112115599B (en
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于斌
刘梓昌
苏铭
姚强岭
贾渊
夏泽
白一宁
马军强
左超红
李耀晖
张冠宇
孙浩
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China University of Mining and Technology CUMT
Datong Coal Mine Group Co Ltd
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Datong Coal Mine Group Co Ltd
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Abstract

本发明公开了一种密集钻孔弱化顶板孔间距计算方法,首先根据钻孔周围岩体塑性区的边界推导得到单个钻孔周围塑性区发育半径的理论计算公式;在塑性区发育计算公式中考虑到实际工程对塑性区发育的影响,得到钻孔周围岩体原位岩石力学性能;同时对钻孔周围的围岩破碎程度进行分级以确定放大系数,进而计算得到密集钻孔塑性区发育半径;最后可以确定密集钻孔弱化顶板孔间距。合理的密集钻孔孔间距可以使得钻孔的卸压区相互叠加、互相连通,从而形成人工岩体结构弱化带。本发明在保证了弱化顶板效果的同时,可有效的控制密集钻孔的孔间距大小,极大的减轻了施工作业工作量,进一步提高了矿井安全系数及生产效率。The invention discloses a method for calculating the spacing between densely drilled and weakened roofs. First, the theoretical calculation formula of the development radius of the plastic zone around a single drill hole is derived according to the boundary of the plastic zone of the rock mass around the drill hole; the calculation formula for the development of the plastic zone is considered According to the influence of actual engineering on the development of plastic zone, the in-situ rock mechanical properties of the rock mass around the borehole are obtained; at the same time, the degree of fragmentation of the surrounding rock around the borehole is classified to determine the amplification factor, and then the development radius of the dense borehole plastic zone is calculated; Finally, it is possible to determine the spacing between dense drilling and weakening the roof holes. Reasonable dense drilling hole spacing can make the pressure relief areas of the drilling holes overlap and connect with each other, thereby forming a weakened zone of artificial rock mass structure. While ensuring the effect of weakening the roof, the invention can effectively control the hole spacing of the dense drilling, greatly reduce the construction workload, and further improve the mine safety factor and production efficiency.

Description

一种密集钻孔弱化顶板孔间距计算方法A method for calculating the spacing between densely drilled and weakened roofs

技术领域technical field

本发明属于矿山顶板岩层控制技术领域,尤其涉及一种密集钻孔弱化顶板孔间距计算方法。The invention belongs to the technical field of mine roof rock formation control, and in particular relates to a method for calculating the spacing between densely drilled and weakened roof holes.

背景技术Background technique

弱化顶板通过改变顶板岩体的物理力学性质,减小顶板悬露面积,防止或减弱大面积顶板来压,以达到工作面安全、高效生产,是矿山综采的重要手段。The weakened roof is an important means of fully mechanized mining by changing the physical and mechanical properties of the roof rock mass, reducing the overhang area of the roof, preventing or weakening the pressure of a large area of the roof, so as to achieve safe and efficient production of the working face.

目前弱化顶板的常用方法主要有聚能爆破和水力压裂。但聚能爆破难以保证爆破孔孔间切缝率和爆破裂缝方向,存在爆破可控性低、对巷道围岩扰动影响严重等问题,且不适用于高瓦斯矿井。水力压裂虽然对巷道围岩扰动较小,适用性强,但是裂缝角度、裂缝高度、裂缝贯穿率有限,现场操作复杂,学习成本较高。针对以上问题有学者提出密集钻孔弱化顶板切顶卸压技术能够有效弥补上述方法的部分缺陷,能够有效解决煤矿深部开采沿空留巷过程中小煤柱开采时冲击地压过大的问题;也能够针对采空区坚硬顶板无法及时垮落、顶板内弹性势能大量积聚的情况,及时切顶卸压。但目前该方法对密集钻孔施工时孔间距的具体参数并未有科学计算方法。钻孔间距作为该技术的关键参数,若选取的孔间距太大,则不能满足顶板弱化的要求,无法达到卸压的效果;若选取的孔间距太小,虽然可以达到顶板弱化卸压效果,但劳动成本会大大增加。At present, the commonly used methods for weakening the roof mainly include shaped blasting and hydraulic fracturing. However, it is difficult for shaped blasting to ensure the cutting rate between blasting holes and the direction of blasting cracks. There are problems such as low blasting controllability and serious disturbance to the surrounding rock of the roadway, and it is not suitable for high gas mines. Although hydraulic fracturing has little disturbance to the surrounding rock of the roadway and has strong applicability, the fracture angle, fracture height and fracture penetration rate are limited, the field operation is complicated, and the learning cost is high. In response to the above problems, some scholars have proposed that the intensive drilling weakened roof cutting and pressure relief technology can effectively make up for some of the defects of the above methods, and can effectively solve the problem of excessive ground pressure during small coal pillar mining in the process of gob-side entry retention in deep coal mining. In view of the situation that the hard roof in the goaf cannot collapse in time and the elastic potential energy in the roof accumulates a lot, the roof can be cut in time to relieve pressure. However, at present, there is no scientific calculation method for the specific parameters of the hole spacing during intensive drilling construction. The drilling spacing is a key parameter of this technology. If the selected hole spacing is too large, it cannot meet the requirements of roof weakening and cannot achieve the effect of pressure relief; if the selected hole spacing is too small, although the roof weakening pressure relief effect can be achieved, But the labor cost will greatly increase.

发明内容SUMMARY OF THE INVENTION

发明目的:针对以上问题,本发明提出一种密集钻孔弱化顶板孔间距计算方法,可针对不同围岩条件进行钻孔施工间距计算,满足实际工程需要。Purpose of the invention: In view of the above problems, the present invention proposes a method for calculating the spacing between holes in a weakened roof with dense drilling, which can calculate the spacing between drilling holes according to different surrounding rock conditions and meet actual engineering needs.

技术方案:为实现本发明的目的,本发明所采用的技术方案是:一种密集钻孔弱化顶板孔距计算方法,包括如下步骤:Technical scheme: In order to achieve the purpose of the present invention, the technical scheme adopted in the present invention is: a method for calculating the distance between densely drilled and weakened roof plates, comprising the following steps:

S1,根据钻孔围岩受力情况,设定整个钻孔径向的受力作用一致,参考图6,以钻孔中心为圆心,建立二维极坐标系;S1, according to the force of the surrounding rock of the borehole, set the radial force of the entire borehole to be consistent. Referring to Figure 6, the center of the borehole is taken as the center of the circle to establish a two-dimensional polar coordinate system;

S2,根据弹性力学,极坐标下钻孔周围岩体的应力分量的公式为:S2, according to elastic mechanics, the formula for the stress component of the rock mass around the borehole in polar coordinates is:

Figure BDA0002675240670000011
Figure BDA0002675240670000011

式中,ρ为钻孔周围岩体任意一点的极坐标值;a为钻孔半径,mm;P为钻孔所在位置的水平地应力,MPa;σρ为钻孔周围岩体任意一点处的径向应力,MPa;σθ为钻孔周围岩体任意一点处的环向应力,MPa;τρ为钻孔周围岩体任意一点处的径向剪应力,MPa;τθ为钻孔周围岩体任意一点处的环向剪应力,MPa;In the formula, ρ is the polar coordinate value of any point of the rock mass around the borehole; a is the radius of the borehole, mm; P is the horizontal in-situ stress at the location of the borehole, MPa; σ ρ is the value of any point of the rock mass around the borehole Radial stress, MPa; σ θ is the hoop stress at any point of the rock mass around the borehole, MPa; τ ρ is the radial shear stress at any point of the rock mass around the borehole, MPa; τ θ is the rock around the borehole hoop shear stress at any point of the body, MPa;

S3,根据平衡条件和莫尔强度条件,基于步骤S2所述参数σρ、σθ和τρ,得到钻孔周围岩体中任意一点所在平面状态的极值应力公式为:S3, according to the equilibrium condition and Moiré strength condition, and based on the parameters σ ρ , σ θ and τ ρ described in step S2, the extreme value stress formula of the plane state where any point in the rock mass around the borehole is obtained is:

Figure BDA0002675240670000021
Figure BDA0002675240670000021

式中,σ1为钻孔周围岩体任意一点处平面内的最大主应力,MPa;σ2为钻孔周围岩体任意一点处平面内的最小主应力,MPa;σρ为钻孔周围岩体任意一点处的径向应力,MPa;σθ为钻孔周围岩体任意一点处的环向应力,MPa;τρ为钻孔周围岩体任意一点处的径向剪应力,MPa;In the formula, σ 1 is the maximum principal stress in the plane at any point of the rock mass around the borehole, MPa; σ 2 is the minimum principal stress in the plane at any point of the rock mass around the borehole, MPa; σ ρ is the rock around the borehole. radial stress at any point of the body, MPa; σ θ is the hoop stress at any point of the rock mass around the borehole, MPa; τ ρ is the radial shear stress at any point of the rock mass around the borehole, MPa;

进一步地,列出钻孔周围岩体在该平面上所受剪应力值τn和钻孔周围岩体在该平面上所受正应力σn的常用求解公式为:Further, the commonly used solution formula for listing the shear stress value τ n of the rock mass around the borehole on the plane and the normal stress σ n of the rock mass around the borehole on the plane is:

Figure BDA0002675240670000022
Figure BDA0002675240670000022

式中,τn为钻孔周围岩体在该平面上所受剪应力值,MPa;σn为钻孔周围岩体在该平面上所受正应力,MPa;σ1为钻孔周围岩体任意一点处平面内的最大主应力,MPa;σ2为钻孔周围岩体任意一点处平面内的最小主应力,MPa;In the formula, τ n is the shear stress value of the rock mass around the borehole on the plane, MPa; σ n is the normal stress of the rock mass around the borehole on the plane, MPa; σ 1 is the rock mass around the borehole The maximum principal stress in the plane at any point, MPa; σ 2 is the minimum principal stress in the plane at any point of the rock mass around the borehole, MPa;

同时根据莫尔—库伦屈服条件,即岩体某个平面上的剪应力τn达到极限值时,岩体发生屈服;而该极限值与钻孔周围岩体损伤后的内聚力C、钻孔周围岩体的内摩擦角

Figure BDA0002675240670000026
及钻孔周围岩体在该平面上所受正应力σn有关,公式为:At the same time, according to the Mohr-Coulomb yield condition, that is, when the shear stress τ n on a certain plane of the rock mass reaches the limit value, the rock mass yields; Internal friction angle of rock mass
Figure BDA0002675240670000026
It is related to the normal stress σ n of the rock mass around the borehole on the plane, and the formula is:

Figure BDA0002675240670000023
Figure BDA0002675240670000023

式中,τn为钻孔周围岩体在该平面上所受剪应力值,MPa;C为钻孔周围岩体损伤后的内聚力,MPa;σn为钻孔周围岩体在该平面上所受正应力,MPa;

Figure BDA0002675240670000024
为钻孔周围岩体的内摩擦角,度;In the formula, τ n is the shear stress value of the rock mass around the borehole on the plane, MPa; C is the cohesive force of the rock mass around the borehole after damage, MPa; σ n is the rock mass around the borehole on the plane. Under normal stress, MPa;
Figure BDA0002675240670000024
is the internal friction angle of the rock mass around the borehole, degrees;

进一步地,公式(2)、公式(3)和公式(4)联立可得到钻孔周围岩体任意一点的屈服条件式:Further, formula (2), formula (3) and formula (4) can be combined to obtain the yield condition formula of any point of the rock mass around the borehole:

Figure BDA0002675240670000025
Figure BDA0002675240670000025

式中,σρ为钻孔周围岩体任意一点处的径向应力,MPa;σθ为钻孔周围岩体任意一点处的环向应力,MPa;τρ为钻孔周围岩体任意一点处的径向剪应力,MPa;C为钻孔周围岩体损伤后的内聚力,MPa;

Figure BDA0002675240670000031
为钻孔周围岩体的内摩擦角,度。In the formula, σ ρ is the radial stress at any point of the rock mass around the borehole, MPa; σ θ is the hoop stress at any point of the rock mass around the borehole, MPa; τ ρ is any point of the rock mass around the borehole The radial shear stress of , MPa; C is the cohesive force of the rock mass around the borehole after damage, MPa;
Figure BDA0002675240670000031
is the internal friction angle of the rock mass around the borehole, degrees.

S4,根据钻孔周围岩体的应力分布规律和弹性理论,钻孔周围岩体的应力状态满足屈服条件时得到钻孔塑性区的发育半径,即联立步骤S2所述公式(1)和步骤S3所述公式(5),得到钻孔周围岩体塑性区的发育半径的计算公式:S4, according to the stress distribution law and elastic theory of the rock mass around the borehole, when the stress state of the rock mass around the borehole satisfies the yield condition, the development radius of the borehole plastic zone is obtained, that is, the formula (1) and the step of step S2 are combined. The formula (5) described in S3, the calculation formula of the development radius of the plastic zone of the rock mass around the borehole is obtained:

Figure BDA0002675240670000032
Figure BDA0002675240670000032

式中:R为钻孔周围岩体弹塑性区边界线上的任意一点的极坐标值;ρ为钻孔周围岩体任意一点的极坐标值;a为钻孔半径,mm;C为钻孔周围岩体损伤后的内聚力,MPa;

Figure BDA0002675240670000033
为钻孔周围岩体的内摩擦角,度;P为钻孔所在位置的水平地应力,MPa;In the formula: R is the polar coordinate value of any point on the boundary line of the elastic-plastic zone of the rock mass around the borehole; ρ is the polar coordinate value of any point of the rock mass around the borehole; a is the radius of the borehole, mm; C is the borehole Cohesion of surrounding rock mass after damage, MPa;
Figure BDA0002675240670000033
is the internal friction angle of the rock mass around the borehole, degrees; P is the horizontal in-situ stress at the location of the borehole, MPa;

S5,基于步骤S4所述钻孔塑性区的发育半径,得到密集钻孔弱化顶板孔间距的计算公式为:S5, based on the development radius of the borehole plastic zone described in step S4, the calculation formula for obtaining the spacing between the densely drilled and weakened roof holes is:

L=2Ru (7)L=2Ru (7)

式中,L为密集钻孔弱化顶板孔间距,mm;R为钻孔周围岩体弹塑性区边界线上的任意一点的极坐标值;u为钻孔交界半径放大系数,可根据地质条件的不同取1.2-1.6;In the formula, L is the distance between the holes in the weakened roof of the dense drilling, mm; R is the polar coordinate value of any point on the boundary line of the elastic-plastic zone of the rock mass around the drilling; Different take 1.2-1.6;

有益效果:与现有技术相比,本发明的技术方案具有以下有益的技术效果:Beneficial effects: compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

本发明提出了一种密集钻孔弱化顶板孔间距的计算方法,基于岩石的弹-脆-塑模型及摩尔库伦准则,计算单孔的塑性区发育情况,并综合考虑多重影响因素,计算得到合适的孔间距,使得密集钻孔岩体的塑性区能相互叠加、互相连通,形成人工岩体结构弱化带,科学有效的解决煤矿深部开采过程中,开采时冲击地压过大的问题;并能够用于放顶煤强制放顶等强矿压问题。The invention proposes a method for calculating the spacing between densely drilled and weakened roof holes. Based on the elastic-brittle-plastic model of rock and the Mohr Coulomb criterion, the development of the plastic zone of a single hole is calculated, and multiple influencing factors are comprehensively considered to obtain a suitable calculation method. The hole spacing of the densely drilled rock mass can be superimposed and connected with each other to form a weakened zone of artificial rock mass structure, which can scientifically and effectively solve the problem of excessive ground pressure during mining in the deep mining process of coal mines; It is used for strong rock pressure problems such as forced top caving caving.

附图说明Description of drawings

图1是密集钻孔弱化顶板切顶卸压方法的钻孔布置平面图;Fig. 1 is the plan view of the drilling arrangement of the method of intensive drilling to weaken the roof cutting and pressure relief;

图2是图1中I-I向剖视图;Fig. 2 is the sectional view of I-I in Fig. 1;

图3是钻孔成像仪示意图;Figure 3 is a schematic diagram of a borehole imager;

图4是原位岩石钻孔剪切仪示意图;Fig. 4 is the schematic diagram of in-situ rock drilling shearing instrument;

图5是水压致裂原位地应力测试系统示意图;Figure 5 is a schematic diagram of a hydraulic fracturing in-situ stress test system;

图6是单个钻孔的围岩的弹塑性区发育图;Fig. 6 is the development diagram of the elastic-plastic zone of the surrounding rock of a single borehole;

图7是密集钻孔弱化顶板构成人工弱化带示意图;Fig. 7 is the schematic diagram of the artificial weakening zone formed by the densely drilled weakened roof;

图中,1-上区段巷道;2-上区段工作面;3-采空区;4-下区段工作面;5-巷道切顶卸压密集钻孔;6-直接顶;7-强制放顶密集钻孔。In the figure, 1- upper section roadway; 2- upper section working face; 3- goaf; 4- lower section working face; 5- roadway roof cutting and pressure relief intensive drilling; 6- direct roof; 7- Forced caving for dense drilling.

具体实施方式Detailed ways

下面结合附图和实施例对本发明的技术方案作进一步的说明。其中,所描述的实施例是本发明一部分实施例,而不是全部的实施例。因此,以下对在附图中提供的本发明的实施例的详细描述并非旨在限制要求保护的本发明的范围,而是仅仅表示本发明的选定实施例。The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments. Herein, the described embodiments are some, but not all, embodiments of the present invention. Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention.

本发明所述的一种密集钻孔弱化顶板孔间距计算方法是密集钻孔顶板弱化的重要参数计算方法。密集钻孔弱化顶板这一技术可应用于坚硬顶板切顶卸压及放顶煤强制放顶等,通过密集钻孔形成人工弱化带,在岩体自重或采动的不平衡高应力影响下,顶板能够沿此弱化带切落或顶煤开始垮落。下面以某矿的地质条件为例对密集钻孔的孔间距进行计算:The method for calculating the hole spacing of the densely drilled weakened roof according to the present invention is an important parameter calculation method for the weakening of the densely drilled roof. The technology of intensive drilling to weaken the roof can be applied to hard roof cutting and pressure relief and forced roof caving, etc. The artificial weakening zone is formed through intensive drilling. The roof can be cut off along this weakened zone or the top coal begins to slump. The following takes the geological conditions of a mine as an example to calculate the hole spacing of dense drilling:

S1,回采工作面布置方式参考图1和图2,为了使回采工作面的直接顶6及时垮落,降低严空巷道的维护难度,选择在上区段工作面巷道沿煤柱一侧的顶板布置巷道切顶卸压密集钻孔5,密集钻孔半径为30mm,巷道切顶卸压密集钻孔5沿着巷道的延伸方向,垂直于巷道直接顶6;若要对工作面放顶煤强制放顶可在回采工作面靠近煤壁处布设强制放顶密集钻孔7。S1, refer to Figure 1 and Figure 2 for the arrangement of the working face. In order to make the direct roof 6 of the working face collapse in time and reduce the maintenance difficulty of the strict-gap roadway, the roof on the side of the coal column in the upper section of the working face is selected. Arrange the roadway roof cutting and pressure relief intensive drilling holes 5, the radius of the intensive drilling holes is 30mm, the roadway roof cutting pressure relief intensive drilling holes 5 are along the extension direction of the roadway, and are perpendicular to the roadway directly roof 6; For roof caving, intensive drilling holes 7 for forced caving can be arranged near the coal wall in the mining face.

S2,对相关顶板围岩在开采扰动影响下岩石力学参数进行准确测量,在超前开切眼5-10m内布设原位测试孔;参考图4,采用井下原位测试系统实测获得巷道开挖后工作面回采影响下,顶板围岩钻孔周围岩体损伤后的内聚力C为1.1MPa、钻孔周围岩体的内摩擦角

Figure BDA0002675240670000041
为30°;参考图5,采用水压致裂原位地应力测试系统得到该矿顶板围岩的地应力为14MPa;参考图3,通过钻孔窥视仪对单一钻孔后一定时间内围岩裂隙发育程度进行分析,参考图7,考虑密集钻孔的群体效应,根据围岩裂隙发育情况及密集钻孔相互耦合作用选定放大系数u取1.5。S2. Accurately measure the rock mechanical parameters of the relevant roof surrounding rock under the influence of mining disturbance, and arrange in-situ test holes within 5-10m of the advance cutting hole; referring to Figure 4, the underground in-situ test system is used to obtain the roadway after excavation. Under the influence of working face mining, the cohesive force C of the damaged rock mass around the roof surrounding rock is 1.1 MPa, and the internal friction angle of the rock mass around the drilling is 1.1 MPa.
Figure BDA0002675240670000041
is 30°; with reference to Figure 5, the in-situ stress of the roof surrounding rock of the mine is 14MPa obtained by the hydraulic fracturing in-situ stress test system; with reference to Figure 3, the surrounding rock within a certain period of time after a single drill hole is drilled through a borehole peep instrument The degree of fissure development is analyzed. Referring to Figure 7, considering the group effect of dense drilling, the amplification factor u is selected to be 1.5 according to the development of fissures in the surrounding rock and the mutual coupling effect of dense drilling.

S3,参考图6,根据钻孔围岩受力情况,设定整个钻孔径向的受力作用一致,以钻孔中心为圆心,建立二维极坐标系;根据弹性力学得到极坐标下钻孔周围岩体中的应力分量公式为:S3, refer to Fig. 6, according to the force of the surrounding rock of the borehole, set the radial force of the entire borehole to be the same, take the center of the borehole as the center of the circle, and establish a two-dimensional polar coordinate system; obtain the polar coordinates according to the elastic mechanics to drill down The formula for the stress component in the rock mass around the hole is:

Figure BDA0002675240670000042
Figure BDA0002675240670000042

式中,ρ为钻孔周围岩体任意一点的极坐标值;a为钻孔半径,mm;P为钻孔所在位置的水平地应力,MPa;σρ为钻孔周围岩体任意一点处的径向应力,MPa;σθ为钻孔周围岩体任意一点处的环向应力,MPa;τρ为钻孔周围岩体任意一点处的径向剪应力,MPa;τθ为钻孔周围岩体任意一点处的环向剪应力,MPa;In the formula, ρ is the polar coordinate value of any point of the rock mass around the borehole; a is the radius of the borehole, mm; P is the horizontal in-situ stress at the location of the borehole, MPa; σ ρ is the value of any point of the rock mass around the borehole Radial stress, MPa; σ θ is the hoop stress at any point of the rock mass around the borehole, MPa; τ ρ is the radial shear stress at any point of the rock mass around the borehole, MPa; τ θ is the rock around the borehole hoop shear stress at any point of the body, MPa;

S4,根据平衡条件和莫尔强度条件,基于步骤S3所述参数σρ、σθ和τρ,得到钻孔周围岩体中任意一点所在平面状态的极值应力公式为:S4, according to the equilibrium condition and Moiré strength condition, based on the parameters σ ρ , σ θ and τ ρ described in step S3, the extreme value stress formula of the plane state where any point in the rock mass around the borehole is obtained is:

Figure BDA0002675240670000051
Figure BDA0002675240670000051

式中,σ1为钻孔周围岩体任意一点处平面内的最大主应力,MPa;σ2为钻孔周围岩体任意一点处平面内的最小主应力,MPa;σρ为钻孔周围岩体任意一点处的径向应力,MPa;σθ为钻孔周围岩体任意一点处的环向应力,MPa;τρ为钻孔周围岩体任意一点处的径向剪应力,MPa;In the formula, σ 1 is the maximum principal stress in the plane at any point of the rock mass around the borehole, MPa; σ 2 is the minimum principal stress in the plane at any point of the rock mass around the borehole, MPa; σ ρ is the rock around the borehole. radial stress at any point of the body, MPa; σ θ is the hoop stress at any point of the rock mass around the borehole, MPa; τ ρ is the radial shear stress at any point of the rock mass around the borehole, MPa;

进一步地,列出钻孔周围岩体在该平面上所受剪应力值τn和钻孔周围岩体在该平面上所受正应力σn的常用求解公式为:Further, the commonly used solution formula for listing the shear stress value τ n of the rock mass around the borehole on the plane and the normal stress σ n of the rock mass around the borehole on the plane is:

Figure BDA0002675240670000052
Figure BDA0002675240670000052

式中,τn为钻孔周围岩体在该平面上所受剪应力值,MPa;σn为钻孔周围岩体在该平面上所受正应力,MPa;σ1为钻孔周围岩体任意一点处平面内的最大主应力,MPa;σ2为钻孔周围岩体任意一点处平面内的最小主应力,MPa;In the formula, τ n is the shear stress value of the rock mass around the borehole on the plane, MPa; σ n is the normal stress of the rock mass around the borehole on the plane, MPa; σ 1 is the rock mass around the borehole The maximum principal stress in the plane at any point, MPa; σ 2 is the minimum principal stress in the plane at any point of the rock mass around the borehole, MPa;

同时根据莫尔—库伦屈服条件,即岩体某个平面上的剪应力达到极限值时,岩体发生屈服;而该极值与钻孔周围岩体损伤后的内聚力C、钻孔周围岩体的内摩擦角

Figure BDA0002675240670000056
及钻孔周围岩体在该平面上所受正应力σn有关,公式为:At the same time, according to the Mohr-Coulomb yield condition, that is, when the shear stress on a certain plane of the rock mass reaches the limit value, the rock mass yields; angle of internal friction
Figure BDA0002675240670000056
It is related to the normal stress σ n of the rock mass around the borehole on the plane, and the formula is:

Figure BDA0002675240670000053
Figure BDA0002675240670000053

式中,τn为钻孔周围岩体在该平面上所受剪应力值,MPa;C钻孔周围岩体损伤后的内聚力,MPa;σn为钻孔周围岩体在该平面上所受正应力,MPa;

Figure BDA0002675240670000054
为钻孔周围岩体的内摩擦角,度;In the formula, τ n is the shear stress value of the rock mass around the borehole on the plane, MPa; C is the cohesive force of the rock mass around the borehole after damage, MPa; σ n is the rock mass around the borehole on this plane. Normal stress, MPa;
Figure BDA0002675240670000054
is the internal friction angle of the rock mass around the borehole, degrees;

进一步地,公式(2)、公式(3)和公式(4)联立可得到钻孔周围岩体任意一点的屈服条件式:Further, formula (2), formula (3) and formula (4) can be combined to obtain the yield condition formula of any point of the rock mass around the borehole:

Figure BDA0002675240670000055
Figure BDA0002675240670000055

式中,σρ为钻孔周围岩体任意一点处的径向应力,MPa;σθ为钻孔周围岩体任意一点处的环向应力,MPa;τρ为钻孔周围岩体任意一点处的径向剪应力,MPa;C钻孔周围岩体损伤后的内聚力,MPa;

Figure BDA0002675240670000061
为钻孔周围岩体的内摩擦角,度。In the formula, σ ρ is the radial stress at any point of the rock mass around the borehole, MPa; σ θ is the hoop stress at any point of the rock mass around the borehole, MPa; τ ρ is any point of the rock mass around the borehole radial shear stress of , MPa; cohesive force of rock mass around borehole C after damage, MPa;
Figure BDA0002675240670000061
is the internal friction angle of the rock mass around the borehole, degrees.

S5,根据钻孔周围岩体的应力分布规律和弹性理论,钻孔周围岩体的应力状态满足屈服条件时得到钻孔塑性区的发育半径,即联立步骤S3所述公式(1)和步骤S4所述公式(5),得到钻孔周围岩体塑性区的发育半径的计算公式:S5, according to the stress distribution law and elasticity theory of the rock mass around the borehole, when the stress state of the rock mass around the borehole satisfies the yield condition, the development radius of the borehole plastic zone is obtained, that is, the formula (1) and the step of step S3 are combined. The formula (5) described in S4, the calculation formula of the development radius of the plastic zone of the rock mass around the borehole is obtained:

Figure BDA0002675240670000062
Figure BDA0002675240670000062

式中:R为钻孔周围岩体弹塑性区边界线上的任意一点的极坐标值;ρ为钻孔周围岩体任意一点的极坐标值;a为钻孔半径,mm;C钻孔周围岩体损伤后的内聚力,MPa;

Figure BDA0002675240670000063
为钻孔周围岩体的内摩擦角,度;P为钻孔所在位置的水平地应力,MPa;In the formula: R is the polar coordinate value of any point on the boundary line of the elastic-plastic zone of the rock mass around the borehole; ρ is the polar coordinate value of any point of the rock mass around the borehole; a is the radius of the borehole, mm; C around the borehole Cohesion of rock mass after damage, MPa;
Figure BDA0002675240670000063
is the internal friction angle of the rock mass around the borehole, degrees; P is the horizontal in-situ stress at the location of the borehole, MPa;

S6,基于步骤S5所述钻孔塑性区的发育半径,得到密集钻孔弱化顶板孔间距的计算公式为:S6, based on the development radius of the drilling plastic zone described in step S5, the calculation formula for obtaining the spacing between the holes of the densely drilled weakened roof is:

L=2Ru (7)L=2Ru (7)

式中,L为密集钻孔弱化顶板孔间距,mm;R为钻孔周围岩体弹塑性区边界线上的任意一点的极坐标值;u为钻孔交界半径放大系数,本式u取值1.5;In the formula, L is the distance between the holes in the weakened roof of the dense drilling hole, mm; R is the polar coordinate value of any point on the boundary line of the elastic-plastic zone of the rock mass around the drilling hole; u is the magnification factor of the boundary radius of the drilling hole, which is the value of u in this formula 1.5;

基于步骤S5所述参数R和步骤S6所述参数u,计算得到密集钻孔弱化顶板孔间距L=119mm,由于工程施工中存在一定误差,考虑到容差,密集钻孔选择110-130mm为钻孔间距。Based on the parameter R described in step S5 and the parameter u described in step S6, the distance L=119mm between the holes in the weakened roof of the dense drilling is calculated. Due to certain errors in the engineering construction, considering the tolerance, the dense drilling is selected as 110-130 mm. hole spacing.

Claims (5)

1.一种密集钻孔弱化顶板孔间距计算方法,其特征在于,所述方法具体包括如下步骤:1. a method for calculating the distance between densely drilled and weakened roof holes, is characterized in that, the method specifically comprises the steps: S1:根据钻孔围岩受力情况,设定整个钻孔径向的受力作用一致,以钻孔中心为圆心,建立二维极坐标系;S1: According to the force of the surrounding rock of the borehole, set the radial force of the entire borehole to be consistent, and establish a two-dimensional polar coordinate system with the center of the borehole as the center of the circle; S2:根据弹性力学,得到极坐标下钻孔周围岩体的应力分量的公式;S2: According to elastic mechanics, the formula of the stress component of the rock mass around the borehole in polar coordinates is obtained; S3:根据平衡条件和莫尔强度条件得到钻孔周围岩体任意一点所在平面状态的极值应力公式,根据钻孔周围岩体在满足莫尔—库伦屈服条件时,结合钻孔周围岩体的原岩应力,计算得到钻孔周围岩体任意一点的屈服条件式;S3: According to the equilibrium conditions and Mohr strength conditions, the extreme stress formula of the plane state of any point of the rock mass around the borehole is obtained. According to the Mohr-Coulomb yield condition of the rock mass around the borehole, combined with the The original rock stress can be calculated to obtain the yield condition formula of any point of the rock mass around the borehole; S4:根据弹性理论,由满足屈服条件时的钻孔周围岩体的应力状态计算得到塑性区的发育半径的计算公式;S4: According to the theory of elasticity, the calculation formula of the development radius of the plastic zone is obtained by calculating the stress state of the rock mass around the borehole when the yield condition is satisfied; S5:基于步骤S4所述塑性区的发育半径,计算得到密集钻孔弱化顶板孔间距的数值。S5: Based on the development radius of the plastic zone described in step S4, calculate and obtain the numerical value of the spacing between the holes in the weakened roof plate by dense drilling. 2.根据权利要求1所述的一种密集钻孔弱化顶板孔间距计算方法,其特征在于:步骤S2在该坐标系下钻孔周围岩体的应力分量的公式如下:2. a kind of intensive drilling weakening roof hole spacing calculation method according to claim 1 is characterized in that: the formula of the stress component of the rock mass around the drilling hole in step S2 is as follows under this coordinate system:
Figure FDA0002675240660000011
Figure FDA0002675240660000011
式中,ρ为钻孔周围岩体任意一点的极坐标值;a为钻孔半径,mm;P为钻孔所在位置的水平地应力,MPa;σρ为钻孔周围岩体任意一点处的径向应力,MPa;σθ为钻孔周围岩体任意一点处的环向应力,MPa;τρ为钻孔周围岩体任意一点处的径向剪应力,MPa;τθ为钻孔周围岩体任意一点处的环向剪应力,MPa。In the formula, ρ is the polar coordinate value of any point of the rock mass around the borehole; a is the radius of the borehole, mm; P is the horizontal in-situ stress at the location of the borehole, MPa; σ ρ is the value of any point of the rock mass around the borehole Radial stress, MPa; σ θ is the hoop stress at any point of the rock mass around the borehole, MPa; τ ρ is the radial shear stress at any point of the rock mass around the borehole, MPa; τ θ is the rock around the borehole Hoop shear stress at any point of the body, MPa.
3.根据权利要求2所述的一种密集钻孔弱化顶板孔间距计算方法,其特征在于:步骤S3的具体操作步骤如下:3. a kind of intensive drilling weakening roof hole spacing calculation method according to claim 2 is characterized in that: the concrete operation steps of step S3 are as follows: S3.1:根据平衡条件和莫尔强度条件,得到钻孔周围岩体中任意一点所在平面状态的极值应力公式为:S3.1: According to the equilibrium conditions and Mohr strength conditions, the extreme stress formula of the plane state at any point in the rock mass around the borehole is obtained as:
Figure FDA0002675240660000012
Figure FDA0002675240660000012
式中,σ1为钻孔周围岩体任意一点处平面内的最大主应力,MPa;σ2为钻孔周围岩体任意一点处平面内的最小主应力,MPa;σρ为钻孔周围岩体任意一点处的径向应力,MPa;σθ为钻孔周围岩体任意一点处的环向应力,MPa;τρ为钻孔周围岩体任意一点处的径向剪应力,MPa;In the formula, σ 1 is the maximum principal stress in the plane at any point of the rock mass around the borehole, MPa; σ 2 is the minimum principal stress in the plane at any point of the rock mass around the borehole, MPa; σ ρ is the rock around the borehole. radial stress at any point of the body, MPa; σ θ is the hoop stress at any point of the rock mass around the borehole, MPa; τ ρ is the radial shear stress at any point of the rock mass around the borehole, MPa; S3.2:根据莫尔—库伦屈服条件,即岩体在某个平面上的剪应力达到极限值时,岩体发生屈服;得到该极值关于钻孔周围岩体损伤后的内聚力C、钻孔周围岩体的内摩擦角
Figure FDA0002675240660000021
及钻孔周围岩体在该平面上所受正应力σn的公式为:
S3.2: According to the Mohr-Coulomb yield condition, that is, when the shear stress of the rock mass on a certain plane reaches the limit value, the rock mass yields; the cohesion of the rock mass around the borehole after the damage of the extreme value C, the borehole The internal friction angle of the rock mass around the hole
Figure FDA0002675240660000021
and the normal stress σ n of the rock mass around the borehole on the plane is:
Figure FDA0002675240660000022
Figure FDA0002675240660000022
式中,τn为岩体在该平面上所受剪应力值,MPa;C为钻孔周围岩体损伤后的内聚力,MPa;σn为钻孔周围岩体在该平面上所受正应力,MPa;
Figure FDA0002675240660000023
为钻孔周围岩体的内摩擦角,度;
In the formula, τ n is the shear stress value of the rock mass on the plane, MPa; C is the cohesive force of the rock mass around the borehole after damage, MPa; σ n is the normal stress of the rock mass around the borehole on the plane , MPa;
Figure FDA0002675240660000023
is the internal friction angle of the rock mass around the borehole, degrees;
S3.3:根据钻孔周围岩体任意一点处平面内的主应力计算得到岩体在该平面上所受剪应力值τn和钻孔周围岩体在该平面上所受正应力σn的公式为:S3.3: Calculate the shear stress value τ n of the rock mass on the plane and the normal stress σ n of the rock mass around the borehole on the plane according to the principal stress in the plane at any point of the rock mass around the borehole The formula is:
Figure FDA0002675240660000024
Figure FDA0002675240660000024
式中,τn为岩体在该平面上所受剪应力值,MPa;σn为钻孔周围岩体在该平面上所受正应力,MPa;σ1为钻孔周围岩体任意一点处平面内的最大主应力,MPa;σ2为钻孔周围岩体任意一点处平面内的最小主应力,MPa;In the formula, τ n is the shear stress value of the rock mass on the plane, MPa; σ n is the normal stress of the rock mass around the borehole on the plane, MPa; σ 1 is any point of the rock mass around the borehole The maximum principal stress in the plane, MPa; σ 2 is the minimum principal stress in the plane at any point of the rock mass around the borehole, MPa; S3.4:基于步骤S3.1、S3.2和S3.3所述公式,联立得到钻孔周围岩体任意一点的屈服条件式为:S3.4: Based on the formulas described in steps S3.1, S3.2 and S3.3, the yield condition formula for any point of the rock mass around the borehole is simultaneously obtained as:
Figure FDA0002675240660000025
Figure FDA0002675240660000025
式中,σρ为钻孔周围岩体任意一点处的径向应力,MPa;σθ为钻孔周围岩体任意一点处的环向应力,MPa;τρ为钻孔周围岩体任意一点处的径向剪应力,MPa;C为钻孔周围岩体损伤后的内聚力,MPa;
Figure FDA0002675240660000026
为钻孔周围岩体的内摩擦角,度。
In the formula, σ ρ is the radial stress at any point of the rock mass around the borehole, MPa; σ θ is the hoop stress at any point of the rock mass around the borehole, MPa; τ ρ is any point of the rock mass around the borehole The radial shear stress of , MPa; C is the cohesive force of the rock mass around the borehole after damage, MPa;
Figure FDA0002675240660000026
is the internal friction angle of the rock mass around the borehole, degrees.
4.根据权利要求3所述的一种密集钻孔弱化顶板孔间距计算方法,其特征在于:步骤S4中所述塑性区的发育半径由步骤S2和步骤S3.4所述公式,联立得到塑性区的发育半径的计算公式为:4. A method for calculating the distance between densely drilled and weakened roof holes according to claim 3, characterized in that: the development radius of the plastic zone described in step S4 is obtained from the formulas described in step S2 and step S3.4, which are obtained simultaneously The formula for calculating the development radius of the plastic zone is:
Figure FDA0002675240660000027
Figure FDA0002675240660000027
式中:R为钻孔周围岩体弹塑性区边界线上的任意一点的极坐标值;ρ为钻孔周围岩体任意一点的极坐标值;a为钻孔半径,mm;C为钻孔周围岩体损伤后的内聚力,MPa;
Figure FDA0002675240660000031
为钻孔周围岩体的内摩擦角,度;P为钻孔所在位置的水平地应力,MPa。
In the formula: R is the polar coordinate value of any point on the boundary line of the elastic-plastic zone of the rock mass around the borehole; ρ is the polar coordinate value of any point of the rock mass around the borehole; a is the radius of the borehole, mm; C is the borehole Cohesion of surrounding rock mass after damage, MPa;
Figure FDA0002675240660000031
is the internal friction angle of the rock mass around the borehole, degrees; P is the horizontal in-situ stress at the location of the borehole, MPa.
5.根据权利要求4所述的一种密集钻孔弱化顶板孔间距计算方法,其特征在于:步骤S5中所述密集钻孔弱化顶板孔间距的计算公式为:5. a kind of intensive drilling weakened roof hole spacing calculation method according to claim 4 is characterized in that: the calculation formula of intensive drilling weakened roof hole spacing described in step S5 is: L=2RuL=2Ru 式中,L为密集钻孔弱化顶板孔间距,mm;R为钻孔周围岩体弹塑性区边界线上的任意一点的极坐标值;u为钻孔交界半径放大系数。In the formula, L is the distance between the holes in the weakened roof of the dense drilling hole, mm; R is the polar coordinate value of any point on the boundary line of the elastic-plastic zone of the rock mass around the drilling hole; u is the magnification factor of the boundary radius of the drilling hole.
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