Jet Grout Columns Research Articles

Construction Technology and Service Performance of Waterproof Curtain for Foundation Pit in Large-Particle Pebble Gravel Layer of Yangtze River Floodplain

A foundation pit is constructed in the floodplain of Yangtze River, and a deep and thick layer of large-particle pebble gravel exists below the base slab, thus forming a connected supply channel with the adjacent Yangtze River. The large water volume, high water pressure, and strong permeability of this layer bring great risks to the foundation pit construction. In view of the fact that conventional waterproof curtain construction technologies such as the deep mixing column and high-pressure jet grouting column cannot meet the engineering requirements under these kinds of geological and environmental conditions, a new waterproof curtain construction technology that combines the trenching technology of the diaphragm wall with the TRD (Trench cutting Remixing Deep wall) technology is proposed, i.e., the trenching-and-replacing-style TRD technology, as well as the construction process of this technology, is presented. After the waterproof curtain is built using the proposed technology, the strength, integrity, uniformity, and service performance of the waterproof curtain wall are tested and evaluated by the comprehensive methods of coring, borehole television imaging, resistivity CT, and a group well pumping test. The results show that the proposed technology overcomes the adverse effects of underlying large-particle pebble gravel layer, and the waterproof curtain built by it effectively cuts off the hydraulic connection inside and outside the pit. The technical proposal can provide useful references for similar projects.

Pre-Support Method for Horizontal Overlapping Jet Grouting Columns for Very-Large Cross-Section Tunnels in Dry Silty Sand Strata: A Case Study

The Shangbai Tunnel on the Daxi Passenger Dedicated Line passes through unsaturated dry silty sand strata which is prone to sand leakage and gushing after disturbance, posing a significant threat to the safety and progress of construction work. Using the Shangbai Tunnel project as a case study, we conduct laboratory experiments to determine the physical and mechanical properties of dry silty sand layers and analyze the limitations of advanced large pipe shed pre-support and small pipe grouting pre-support structures. The objective is to evaluate the feasibility and reveal the mechanism of horizontal rotary jet grouting for column formation and pre-support. The physical and mechanical properties of the consolidated body of the overlapping columns are evaluated. Three pre-reinforcement schemes using overlapping columns for tunnels crossing different subsurface profiles are proposed. Experiments are conducted to assess the physical and mechanical properties of the overlapping columns, and on-site monitoring and analysis of the tunnel arch settlement and stress changes are performed. The results indicate that the proposed method for creating overlapping columns ensures the stability of the working face, controls arch settlement, and is cost-effective. Our study summarizes the findings from the data and information for the construction of similar projects.

Experimental and theoretical analysis of single-jet column and concrete column using double-jet grouting technique applied at Al-Rashdia site

Abstract Progress in jet grouting technology has been focused on the cutting-edge observer of jets, which aims to generate large columns of jet grouting and increase the activity of construction sites. Since jet grouting techniques vary from conventional grouting methods to modern techniques, they can be used in a variety of soil types and their application areas are expanding quickly. So, grouting methods have become very popular methods for subsoil strengthening. This article includes finding the physical and mechanical properties of the soil of the AL-Rashdia site, using a single-jet grouting machine and a steel model to test concrete piles and jet piles, and a double-jet grouting machine to compare the results obtained from laboratory model of one-dimensional jet grouting column pile with those of a one-dimensional concrete pile. The comparison showed that the settlement of the jet pile was smaller than that of the concrete pile and the bearing load was higher with jet columns giving a high bearing capacity comparable with the concrete pile. Shen’s method is more adequate to find the ultimate bearing load and the settlement for this load. Also, the ultimate pile ratio was 115.63% for the jet column, and the ultimate pile ratio for the concrete column was 123.49%. The compressive strength of the core sample of jet columns was large which improved the bearing capacity of the foundation.

Liquefaction and performance of foundation systems in Iskenderun during 2023 Kahramanmaras-Turkiye earthquake sequence

On February 6, 2023, two devastating earthquakes occurred on the East Anatolian Fault, Turkiye. The earthquakes had severe impacts on civil engineering structures in Iskenderun, Hatay. Reconnaissance studies were performed in Iskenderun to document and evaluate the performances of the different foundation systems and improved ground. Several soil liquefaction cases, including a boulevard, a mosque complex, fishing shelter, and military quarters were observed and documented along with the ground conditions and surface ejecta characteristics. The site observations during the reconnaissance study showed that the application of the unreinforced concrete piles was not a proper foundation solution against seismic loading and did not perform well. Whereas foundation systems including reinforced barrette piles and improved sites with jet grout columns were observed to perform quite well with negligible/no deformations. Observations at several structures indicate that conventional pile foundations also performed well, however structures built on deep foundation systems together with prior jet grout improved sites performed notably better.

Jet grouting column measurement and soil assessment with electric measurements and cross-hole electric tomography

In the context of the construction of the new M3 Bordet-Albert metro line in Brussels, the new Tools Thielemans station will be built near the Gare du Midi. For this purpose, jet grouting work is planned at several sites. Hence, the control of the diameter of the jet grouting columns had to be done in parallel, in constrained conditions, such as, the geographical location in a historical building, the presence of 2m high cellars covering the area of interest, and the length of the columns (over 30 m). The only possible and most reliable methodologies were electric measurements in boreholes to image the reached diameter of the columns and cross-hole electric tomography for determining the electrical resistivities of the in-situ soils and identify heterogeneities in the medium for better parameterizing future jet grouting work.

Diameter Measurement of Jet-Grouting Column Using Geo-Electrical Probe: Construction and Field Testing

Uncertainty about the geometry of jet grouting columns is a serious challenge to the efficiency of jet grouting technology. If this challenge can be met, jet grouting can become an efficient method of soil improvement. One proposed approach is measurement based on changes in the electrical resistivity between the column and surrounding soil. This approach is non-destructive, easy to use, fast and accurate. This paper reviews jet-grouting methods using the experimental research approach and reports on the design and construction of a probe equipped with ring electrodes that is suitable for measurement of the column diameter. The approach is based on the geoelectric method and Wenner theory. The probe was field tested on jet-grouting columns in a project in Bandar-e Gaz. The probe results were validated by visually observing the dimensions of the excavated column. The results showed that the probe performed well. The device measured a 90-cm column as being from 81 to 88 cm with an error of about 10%. The method of measuring the difference in electrical resistance was shown to be an accurate approach to solving the problem of uncertainty in the geometry of jet-grouting columns.

Modeling diameter of jet grouting columns using Bayesian framework

AbstractThis study proposes a new model in explicit form to predict the diameter of the jet grouting column of three popular jet grouting systems (i.e., single, double, and triple). The proposed model can quantify the uncertainty associated with the prediction. Bayesian model selection was used to determine the optimal models and, the bootstrap sampling method was adopted to avoid bias in the collected database. The predictions agree well with the measured data, and the 95% credible intervals can cover almost all the measured data on the testing dataset, which indicates the robustness of the proposed model. A simple formula combined with a table was established to facilitate the engineers in applying the proposed model. The results reveal that soil type has a significant impact on diameter prediction. Uncertainty quantification can reveal possible fluctuations in column diameter and is vital to get a cost‐efficient design.

A new prediction model of the jet grouting column diameter for three jet grouting systems

Jet grouting column is widely used in ground improvements of hydraulic and geotechnical structures. Estimation of the diameter of the jet grouting column is indispensable to the design of those structures. Existing prediction models of the jet grouting column perform poorly when applied to the recently emerged double and triple-jet grouting systems and cannot quantify the prediction uncertainties. This study has compiled a global-wide jet grouting database and proposed an explicit model that is suitable for all three popular jet grouting systems (i.e., single, double, and triple). The Bayesian inference method was employed to estimate the regression parameters for the proposed model and quantify the prediction uncertainty. The proposed model is compared with a widely used empirical model through a cross-validation procedure. The comparisons show the proposed model is free of systematic errors and has much higher accuracy than the existing method, although the two have similar complexities in terms of the number of unknown regression parameters. The new model can reasonably quantify the prediction uncertainty in the sense that the 95% confidence interval of jet grouting column diameter covers the actual value with a probability of around 95%. To facilitate practice use, analytical formulas have been derived to calculate the statistics of jet grouting column diameter. This unique feature developed here to quantify the prediction uncertainty provides a potentially fundamentally new tool for engineers to estimate the jet grouting column diameter and assess the associated prediction errors.

A Novel Approach for Assessing the Performance of Offshore Ground Improvement in Floating Storage and Regasification Unit (FSRU) Terminal Construction

A floating storage and regasification unit (FSRU) terminal has been planned to be constructed in Saros Bay (Türkiye). This study presents the ground improvement method using jet grouting to prevent the liquefaction of marine sediments in the project area. An approach for performance assessment of jet column construction is also discussed. The study site has a liquefiable ground level with a thickness changing between 2 m and 8 m. Jet grout columns with an 80 cm diameter were constructed under the sea level, which varied between 4 m and 18 m for ground improvement. The main issue is controlling the quality and performance of these jet columns. Therefore, a practical quality control procedure containing observational, mechanical, and geophysical methods for offshore grouting operations was proposed. The factor of safety values against liquefaction varied between 0.04 and 0.29 for natural conditions, while the minimum factor of safety after jet column constructions was obtained as 1.01. The results of the numerical analyses showed that the constructed terminal has sufficient performance against liquefaction. Consequently, the results of these methods have demonstrated that the jet grout applications performed by following this procedure are a suitable and effective improvement method for offshore soils.

Influence of technological parameters on the properties of jet grouting columns detected with full scale experiments

Influence of technological parameters on the properties of jet grouting columns detected with full scale experiments

Stiffness evolution of jet grouting columns performed under port caissons using PS suspension logging

AbstractJet grouting is one of the ground improvement techniques that are currently more widely used for upgrading gravity quays, especially to increase their berth depth. Irregular columns are formed because of a rotating high‐pressure injection of a cementitious fluid in the ground that mixes with the natural soil. Despite its popularity, there is hardly any field experimentation on the stiffness gain of the mixture, especially under the base of port caissons. As fresh columns behave like a dense fluid with an excess of pore pressure, the evolution of mixture stiffness, especially at early ages after injection, is a key aspect when programming working windows for ground improvement, drill locations, sequencing and timing. Otherwise, crane rails, pavement and other services are at risk of undergoing undesirable local movements. One of the upgrading programs of the Port Authority of Valencia, Spain, is the increase of the berth depth of its quays, many engineered as concrete caissons. The concern about the temporary local loss of the foundation stiffness during the execution of each jet grouting column prompted research to find an in situ procedure capable of measuring the stiffness evolution of the jet grouting columns at early ages. This paper presents a successful procedure using PS suspension logging, expanding its scope of geotechnical engineering applicability in an innovative way. The use of the technique for the intended purpose and the execution process itself stands out as a novelty, with the insertion of the borehole casing pipe through the axis of the recently executed column. The key outcomes of this research are: (1) the novelty of studying the evolution of the stiffness in the early ages of the jet grouting columns executed under port caissons, where it is not possible to execute test columns; and (2) to propose an adequate and reliable method at the beginning of the works to plan the injection sequence of the next columns of jet grouting.

Experimental study to enhance prediction of jet-grout column diameter and efficiency in sand

One of the most significant factors affecting the efficiency of jet-grouting operation is the diameter of the constructed column, depending on soil properties, stress state and operating parameters, including grout pressure (P), grout flow rate (Q), monitor rotational speed (ω) and lifting step (Δs). Increasing treatment efficiency results in a larger diameter with specific energy applied per unit length of the column. In this study, 35 full-scale and small-scale single-fluid jet-grouting elements were constructed in the field and laboratory to investigate the effects of the operating parameters on the diameter and treatment efficiency of the columns constructed in silty sand. Furthermore, measured values and obtained trends were controlled by a comprehensive equation commonly used to predict the diameter of jet-grouting columns. The results indicate that an increase in the time interval per step (Δt) and grout pressure (P), as well as a decrease in the lifting step (Δs), causes a larger column diameter and lower efficiency. However, a decline in rotational speed (ω) improves both diameter and efficiency. Subsequently, the well-known equation has been modified by considering field measurements in this study to predict more-accurate values and trends for both full-scale and small-scale jet-grouting elements.

Assessment of compressive strength of jet grouting by machine learning

Jet grouting is one of the most popular soil improvement techniques, but its design usually involves great uncertainties that can lead to economic cost overruns in construction projects. The high dispersion in the properties of the improved material leads to designers assuming a conservative, arbitrary and unjustified strength, which is even sometimes subjected to the results of the test fields. The present paper presents an approach for prediction of the uniaxial compressive strength (UCS) of jet grouting columns based on the analysis of several machine learning algorithms on a database of 854 results mainly collected from different research papers. The selected machine learning model (extremely randomized trees) relates the soil type and various parameters of the technique to the value of the compressive strength. Despite the complex mechanism that surrounds the jet grouting process, evidenced by the high dispersion and low correlation of the variables studied, the trained model allows to optimally predict the values of compressive strength with a significant improvement with respect to the existing works. Consequently, this work proposes for the first time a reliable and easily applicable approach for estimation of the compressive strength of jet grouting columns.

Control of jet grouting process induced ground displacement in clayey soil

The plasticity and low flowability of spoil discharge from clay soil often result in the clogging of boreholes during jet grouting, thereby causing harmful ground displacement, which damages the normal function and safety of nearby underground infrastructures, pipelines, or overlying structures. This study proposed some control measures for jet grouting in clayey soil which combined with: (a) expanding the cross-section of the spoil exit (or borehole), (b) pre-cutting the surrounding soil with a water jet synchronized with jet grouting, and (c) placing additional guided holes for spoil discharge into the ground surface smoothly. The in-situ grouting test demonstrated that combining the abovementioned measures with the typical jet grouting process could mitigate the borehole clogging issue and minimizes excessive lateral displacement induced by jet grouting in clay layers. More importantly, a series of inspections, measurements, and monitoring results indicated that the proposed measures provide no adverse effects on the effective diameter, strength, and waterproofing of the jet-grouted columns. While the incorporation of the proposed measures into standard jet grouting procedures may result in additional time and construction expenses, it is recommended to implement them in areas where there is a high risk of borehole clogging.

Stiffness Characteristics of Pile Models for Cement Improving Sandy Soil by Low-Pressure Injection Laboratory Setup

Soil improvement has developed as a realistic solution for enhancing soil properties so that structures can be constructed to meet project engineering requirements due to the limited availability of construction land in urban centers. The jet grouting method for soil improvement is a novel geotechnical alternative for problematic soils for which conventional foundation designs cannot provide acceptable and lasting solutions. The paper's methodology was based on constructing pile models using a low-pressure injection laboratory setup built and made locally to simulate the operation of field equipment. The setup design was based on previous research that systematically conducted unconfined compression testing (U.C.Ts.). The soil improvement techniques were investigated by injecting a low-pressure mixture of water and ordinary Portland cement (O.P.C.) with (0.8, 1, and 1.3) W/C ratios. The study revealed the relationship between pile model samples (U.C.Ts.) and W/C ratios. It also showed that the pile model samples' (U.C.Ts.) result decreased from 14 to 12 to 10 MPa, respectively, with an increase in W/C ratios from 0.8 to 1 and 1.3, respectively. Furthermore, the stiffness characteristics of a jet grouting column were calculated based on Mohr's Circles theory, and numerous theoretical approaches obtained the consequences of tensile strength.

Investigation of the Effects of Mixtures of Fly Ash and Cement Types on Jet-Grout Columns

Investigation of the Effects of Mixtures of Fly Ash and Cement Types on Jet-Grout Columns

Full-Scale Loading Test of Jet Grouting in the Artificial Island–Immersed Tunnel Transition Area of the Hong Kong–Zhuhai–Macau Sea Link

In the Hong Kong–Zhuhai–Macau Bridge mega project, several ground treatment methods were applied in the transition area between the artificial island and immersed tube tunnels to reduce the potential uneven foundation settlement underlying the tunnel, as the backfilled sand layer is more than 10 m around it. One of the foundation improvement methods involves the combination of preload and high-pressure jet grouting (HPJG) columns. Current field tests, such as core bowling, standard penetration test, and plate loading test, are not suitable for evaluating the strength of this reinforced foundation. This study presents a full-scale load test to examine the construction quality and effects of an HPJG-reinforced foundation. A novel method was designed based on the Boussinesq equation to simulate the additional stress distribution from the immersed tube tunnel. The tangent modulus method considering the impact of modulus nonlinearity was employed to calculate the nonlinear settlement of the treated foundation. Preferable settlement results were obtained using a set of pre-embedded high-precision hydrostatic leveling systems. Both the measured data and calculated settlement demonstrate the reasonableness of the present in situ test.

Excavation Support and Foundation Ground Improvement Using Jet Grouting Method – A Case Study

One of the soil improvement methods is using soil-cement columns, and one of the most common methods of implementing these columns is the Jet grouting method. In this article, the performance of Jet grouting columns in soil improvement and excavation wall stabilization is investigated in a project located in Chalous, north of Iran, by implementing several experimental soil-cement columns in real scale at depths of 4, 8, and 15 meters and diameter of 80 cm. By comparing the soil settlement before and after the improvement, it was found that the average settlement, which was in the range of 186 mm before the improvement, reached about 68 mm after the improvement using the jet grouting method. It has been observed that the settlement of the foundation has been significantly reduced after improving the ground with soil-cement columns. On the other hand, the results of this study showed that this method has also been very effective in stabilizing the excavation walls. The maximum displacement of the crest of the wall is about 3.4 cm, and the maximum settlement behind the wall is limited to 12 mm.

Enhanced heat extraction performance from deep buried U-shaped well using the high-pressure jet grouting technology

Heat extraction from the single-well geothermal heating system (SWGHS) is significantly restricted by the high thermal resistance of the surrounding host rocks. To improve heat production efficiency of this geothermal system, the high-pressure jet grouting (HPJG) technology is proposed to enhance thermal output in deep buried U-shaped well (DBUSW) system. By means of this technology, an artificial jet grouting column (JGC) with high thermal conductivity is built near the horizontal well segment. The emphasize of this work is to evaluate the feasibility and efficiency of the proposed heat production method. Numerical simulations were conducted via a field validated model from in-situ experiments in Xian. Results demonstrated that average annual heat production rate is improved by about 22% in the 30-year heating period, with building an artificial JGC with 1.0 m radius near the wellbore. These results indicate that the proposed method is a promising strategy for enhancing thermal output in the DBUSW. Sensitivity analyses suggest heat production rate and outlet temperature are mainly controlled by the radius of the JGC, while very high JGC thermal conductivity has less effect. Given the field conditions, the suggested thermal conductivity and radius of artificial JGC is 30 W/m °C and 2.0 m, respectively.

The new museum of the Viking Age – Assessment of vibration from groundworks to avoid damage to artefacts

Construction activities such as blasting, pile driving, compaction, excavations, and construction traffic can cause damage to neighbouring buildings and structures. The situation is even more critical when the nearby buildings are museums with fragile collections. This case study presents vibration assessment work performed in connection with the planning of the construction activities for the planned Museum of the Viking Age on Bygdøy, outside of Oslo, Norway. The planned museum will be built as an extension of the existing Viking Ship Museum, where one of the world's foremost collections of artefacts from the Viking age is displayed. Although the existing museum will be closed during the construction period, objects that are considered too large or too fragile to be temporarily relocated will remain in the museum. Therefore, one of the main challenges during the construction of the new museum is to ensure that vibrations from the ground- and construction work do not damage the fragile objects in the existing museum. Strict vibration limits have been set based on the daily vibration values during normal operation of the museum. The vibration limits are given both as vibration peak limits and as vibration root mean square (RMS). Early calculations showed that especially the RMS limits will be difficult to meet. A “vibration budget” was established, which provides a systematic overview of the vibrations from different construction activities with the expected total time at different RMS levels and with the associated dominating frequency. Based on the results, the most critical construction activities are identified, and effects of mitigation measures are estimated. In addition, the results can form a basis for adjustments of the RMS limits for activities that are expected to last for only a short time. As the main vibration mitigation measure, a screen made of jet-grout columns is planned in the ground between the existing museum and the main construction area. FE-calculations show that the screen may reduce the vibration values by up to 80%. However, since not all activities are affected by the screen, the effect on the vibration budget is somewhat lower.