Study On Dynamic Response Characteristics Of Surrounding Rock Under Excavation Blasting In Underground Gas Storage Caverns

For the construction of large-scale underground caverns,which is under the influence of the traditional construction technique and control of project cost,the most commonly method is still Drilling Blasting Method.During the excavation Blasting,the dynamic response?Dynamic response factor including the vibration velocity,displacement,frequency,energy and stress?of explosion source cavern and adjacent caverns surrounding rock resulted of seismic effect of blasting will easily lead dynamic damage of the explosion source cavern and adjacent caverns surrounding rock,which will also make the surrounding rock mechanics properties degradation and cause adverse effects of the stability of underground caverns surrounding rock.At present the research of underground gas storage caverns is obviously inadequate.The existing research is mainly concentrated in analysis of surrounding rock stability,analysis of seepage field,blasting vibration effect,dynamic response attenuation law and other aspects,which focus on the cavern excavation unloading stress-strain analysis,blasting vibration velocity attenuation rules,safety assessment based on blasting vibration peak velocity and other single point as well as macroscopic rules analysis.And the existing research lacks multi-angle,systematic and internal mechanism research,especially the research of blasting dynamic response characteristics of underground gas storage caverns,which there are few literatures both at home and abroad.According to this situation,during our country's rapid development of construction of underground gas storage caverns,further carrying out study on dynamic response characteristics of surrounding rock under excavation blasting in underground gas storage caverns is a key basic theory problems in engineering application science project and have important practical significance in the large-scale underground gas storage caverns engineering blasting design as well as Construction Security Control.Based on the above understanding,Selecting Yantai Water-Sealed underground rock caverns oil-gas storage?gas storage?as the research object,this paper establish gas storage caverns surrounding rock blasting vibration effect database through field test on blasting vibration test;analyze the sensitivity of caverns surrounding rock blasting vibration effect factors?blast source situation factor and project condition factor?and rank the important degree of influencing factor and reduce-gain the necessary factor by rough set theory;synthetically use support vector machine,fuzzy neural network and traditional empirical formula in uncertainty theory and other methods to optimize and compare the best blasting characteristic parameters prediction model in underground gas storage caverns surrounding rock;apply wavelet decomposition and reconstruction technique and adaptive optimal kernel?AOK?time-frequency analysis technique to analyze the surrounding rock dynamic response's frequency factor and energy factor time-frequency analysis technique.And study the vibration frequency of blasting vibration signal points partial-band,vibration lasting time and the proportion of the seismic wave energy in different blasting source condition as well as different project condition's dynamic response mechanism and evolution laws;Use theoretical analysis and numerical simulation method to master different blasting source condition and different project condition's dynamic response mechanism and evolution rule of surrounding rock vibration velocity factor and stress factor.Establish surrounding rock's dynamic response model?dynamic response function?of peak tensile stress,peak shear stress amplification effects of synthesis peak vibration velocity;Based on the peak equivalent energy theory and surrounding rock dynamic strength criterion,put forward the underground gas storage caverns surrounding rock comprehensive safety criterion that considering blasting vibration velocity factor and frequency factor.And then evaluate the surrounding rock blasting vibration effect and deformation-failure mechanism from multi-angle and systematic.It has important theoretical research sense to the construction of underground gas storage caverns surrounding rock's safety evaluation system.Meanwhile it has significant engineering application value to the gas storage caverns design and construction.The main content includes the following 6 aspects research achievement.1?Blasting vibration field test and analysis of surrounding rock in underground gas storage caverns?1?For peak particle velocity of surrounding rock in underground gas storage caverns,Attenuation law of the traditional Sadov's formula has low correlation that shows anisotropic characteristics along strike direction and its vertical direction of blasting main caverns.?2?For blasting main caverns,the inaccuracy characteristics of the Sadov's formula show that geologic parameter K,? tend to lower limit of value range,the hardness degree characteristic of rock is extremely hard,thus rock mass quality conditions is improved.The reason is the existence of elevation amplification effect.?3?For adjacent main caverns,the inaccuracy characteristics of the Sadov's formula show that tend to lower limit of middle hard rock,thus rock quality conditions is decreased.The reason is that it is difficult for the complexity blasting vibration velocity attenuation rule and dynamics response method in vertical direction of strike direction to use a function expression to describe dynamic respond characteristics.?4?Combined with natural frequency and resonance destruction theory of underground structure,vibration main frequency in vertical direction?Z direction?has significant effect,its influencing mechanism on dynamics response method of gas storage caverns need to be paid close attention to and studied in-depth,as well as considering using blasting scheme optimization measures to control.?5?According to united criterion analytical method,the main vibration frequency and vibration velocity in Blasting vibration data in field blasting vibration test are both reasonable,but it can't determine dynamic stability of surrounding rock in the low frequency vibration signal.2?Study on blasting vibration effect sensitivity of surrounding rock in underground gas storage caverns?1?The necessity influence factors of decision attribute {peak particle velocity V} are distance from explosive source L,difference of elevation H,propagation medium A,maximum charge in one delay time Q,initiation direction D and damping effect of excavated caverns E.?2?The necessity influence factors of the decision attribute {vibration main frequency f} are distance from explosive source L,difference of elevation H,propagation medium A,maximum charge in one delay time Q,millisecond time T,and damping effect of excavated caverns E.?3?The sensitivity of the decision attribute to the condition attribute can be replaced equivalently by non-corresponding ratio.For decision attribute {peak particle velocity V},the range of non-corresponding ratio to condition attribute is 0.095⁰.293;for decision attribute {vibration main frequency f},the range of non-corresponding ratio to condition attribute is 0.086⁰.276.?4?For peak particle velocity V,the importance degree order of influence factors from high to low is maximum charge in one delay time Q>difference of elevation H=distance from explosive source L>propagation medium A=effect of excavated caverns E>initiation direction D>total charge TQ>millisecond time T.?5?For vibration main frequency f,the importance degree order of influence factors from high to low is maximum charge in one delay time Q>effect of excavated caverns E>propagation medium A>distance from explosive source L=difference of elevation H>millisecond time T>initiation direction D>total charge TQ.?6?Importance degree order of blasting vibration effect influence factors of surrounding rock in underground gas storage caverns from high to low is maximum charge in one delay time Q>effect of excavated caverns E>difference of elevation H=distance from explosive source L>propagation medium A>initiation direction D>>millisecond time T>total charge TQ.3?Study on blasting characteristic parameters prediction of surrounding rock in underground gas storage caverns based on uncertainty theory?1?The key parameters obtained from particle swarm optimization-least squares support vector machine?PSO-LSSVM?regression prediction model are more accurate than that from least squares-support vector machine?LS-SVM?in terms of optimized area positions and decimal places,thus working time and effort that optimal key parameters are obtained is greatly reduced and prediction precision is greatly improved.?2?Rough set algorithm fuzzy neural network?RS-FNN?regression prediction model is more compact and independent than fuzzy neural network?FNN?in initial input vector,there have no dummy data,repeating data,and the no-impact condition attribute,thus the number of training and training time which is up to best training model is greatly improved and prediction precision is greatly improved.?3?In the comprehensive comparison evaluation for prediction precision and generalization ability of 5 kinds of models,particle swarm optimization-least squares support vector machine regression prediction model which consider necessity influence factors of blasting vibration effect is determined as best blasting characteristic parameters prediction model of surrounding rock in underground gas storage caverns.4.Study on time frequency characteristics of surrounding rock dynamic response under excavation blasting in underground gas storage caverns?1?For blasting vibration signal,AOK distribution can restrain two-way optimal on resolving accuracy and cross-term suppression in time-varying frequency domain.The best control parameters of AOK time-frequency distribution function: the energy volume index is 2,the window length and width of the window function-radial basis gaussian kernel function is 32 × 32,the FFT resolution is 512,the modulus of time-frequency analysis results is 1.5;?2?The time frequency characteristics of surrounding rock dynamic response under excavation blasting in underground gas storage caverns shows the similar characteristics under the condition of different maximum charge in one delay time,distance from explosive source and difference of elevation: with the increase of maximum charge in one delay time,distance from explosive source and elevation difference,the proportion of the blasting vibration signal in low frequency band increases,which makes the dynamic damage effect of blasting seismic wave increased;the lasting time of the blasting vibration signal frequency duration increases,the low cycle fatigue damage cumulative effect of surrounding rock becomes stronger,which plays a significant role in damage to structure dynamic;the main vibration frequency of low-frequency blasting vibration signal multi-band ranged of 0²00Hz develops to the natural frequency 20 Hz,which makes resonance damage effect of surrounding rock stronger;?3?Under the condition of different damping effect for the excavated cavern,the time frequency characteristics of surrounding rock dynamic response under excavation blasting in underground gas storage caverns shows: With the increase of damping effect for the excavated cavern,the proportion of the blasting vibration signal in high frequency band increases,which converts to blasting acoustic signal and makes the dynamic damage effect of blasting seismic wave on the surrounding rock decreased;the lasting time of the blasting vibration signal frequency duration decreases,the low cycle fatigue damage cumulative effect of surrounding rock becomes weaker;the main vibration frequency of multi-band is far away from the natural frequency,develops to blasting sound frequency,which avoids resonance damage effect of surrounding rock.5.Study on numerical simulation of surrounding rock dynamic response characteristics under excavation blasting in underground gas storage caverns?1?Under the condition of different distances from explosive source,with the increasing of distance from explosive source,the attenuation tendencies of synthesis peak vibration velocity,peak tensile stress and peak shear stress about adjacent main caverns blasting face side and back side all show inverse function curve evolution rule.And then the attenuation tendencies of blasting back side are slower than blasting face side.But the adjacent main caverns particle vibration has nondestructive displacement which is a small displacement vibration located in equilibrium position.?2?Under the condition of different elevation difference,amplification effects of synthesis peak vibration velocity,peak tensile stress and peak shear stress all exist within a certain range of elevation difference increasing.With the elevation difference continues to increase,the elevation amplification effect gradually weakened until disappear.Subsequently,they continue to decrease with the increasing of elevation difference,which show cubic parabola function curve evolution rule.The negative elevation difference direction has the same evolution rule as positive elevation difference direction.But the adjacent main caverns particle vibration has nondestructive displacement which is a small displacement vibration located in equilibrium position.?3?Under the condition of different blasting sources and engineering,surrounding rock in underground gas storage caverns vibration velocity divisor and stress divisor have a special dynamic response model,which show linear function relationship among peak tensile stress and peak shear stress with synthesis peak vibration velocity,the correlation coefficient are 0.871⁰.925 and 0.818⁰.841.6.Study on safety criterion of vibration in underground gas storage caverns?1?Under the dynamic tensile strength criterion of surrounding rock,blasting vibration velocity safety criterion of this engineering ranges from 11.612 to 14.094cm/s.Under the dynamic shear strength criterion of surrounding rock,blasting vibration velocity safety criterion of this engineering ranges from 15.587 to 19.729cm/s.Considering the general applicability of blasting vibration velocity safety criterion,surrounding rock dynamic damage in underground gas storage caverns is mainly tensile failure,the safety criterion of surrounding rock blasting vibration velocity in underground gas storage caverns is 11.612cm/s.?2?According to equivalent peak energy theory,the characteristic equivalent peak energy [E_PE] of blasting earthquake wave in underground gas storage caverns surrounding rock is 16.989,vibrational frequency-vibration velocity comprehensive safety criterions show: in 0²0Hz,the allowable peak vibration velocity is 7.158cm/s;in 20¹00Hz,the allowable peak vibration velocity is 9.162cm/s;in 100²00Hz,the allowable peak vibration velocity is 11.612cm/s.