If you’ve ever worked with construction, mining, or heavy civil projects, you’ve probably heard of the By Opening Method—an excavation technique that relies on carefully controlled, sequential openings to safely remove overburden or reach targeted mineral deposits, rather than blasting through solid rock in a single, unplanned push. As a supplier of the specialized tools, sensors, and custom support packages that power this method, I’ve spent the last eight years walking alongside project managers, geotechnical engineers, and on-site foremen who’ve struggled with one universal challenge: cutting through the noise of fragmented, low-quality data that either delays their timelines, drives up costs, or, worst of all, creates avoidable safety risks. I’ve seen a team scrap a $2.2 million excavation plan because they skipped critical ground stability data, and another finish a job 12 days early because they invested in 3D subsurface mapping before breaking ground. Today, I’m pulling back the curtain on the non-negotiable data requirements for the By Opening Method—data I insist every client provides before we even design a single piece of custom equipment for their job, and data I’ll help source if they don’t already have it. By Opening Method
To start, it’s important to ground this in what makes the By Opening Method unique: unlike traditional excavation that prioritizes speed, this method’s core rule is control. Each opening—whether it’s a pilot tunnel, a side cut, or a face advance—must be spaced and sized to avoid creating stress concentrations that could cause a collapse, rock burst, or even a downstream sinkhole. That means your data can’t be vague or general; it has to answer three basic questions: What is the ground we’re working with? How is that ground behaving now, and how will it change when we excavate? And where exactly are the hidden risks that could derail our work? For years, I’ve worked with suppliers who treat data like a checkbox—collect a few soil samples, run a standard lab test, and call it a day. But from my perspective, data for the By Opening Method is not a checkbox; it’s the foundation of every decision we make, from the type of cutting teeth on our excavator buckets to the spacing of our temporary support structures.
Let’s break down the first and most critical category: subsurface geotechnical data, and I mean high-resolution, site-specific data, not regional average stats pulled from a 10-year-old geological survey. I once had a client who relied on a state-wide geotech report that claimed their site had uniform clay soil, only to discover 18 feet below the surface a layer of fractured shale that had a 27-degree angle of repose—way steeper than the 32 degrees their pilot tunnel design required. The result? They had to pause excavation for three weeks to install additional rock bolts, adding $180,000 in unplanned costs. That’s the kind of mistake that comes from skimping on two specific data points: stratigraphic profiling and discontinuity mapping.
Stratigraphic profiling is simply a detailed map of every layer of earth and rock beneath your site, down to the depth where your final excavation will sit. For the By Opening Method, this isn’t enough to know that “there’s sand at 10 feet and rock at 20 feet.” You need to know the density, cohesion, and friction angle of each layer—properties that tell us how much weight an opening of a certain size can hold. That means we don’t take one soil sample from a boring hole and call it good; we require at least two samples every 5 feet, aligned along the entire path of planned openings. Why? Because even a small change in a layer’s density can mean the difference between a stable opening and a collapse. On a recent mine site in northern Nevada, our client had a 20-foot thick layer of weathered granite that looked uniform from the surface, but their granular sampling revealed a 3-foot zone of heavily fractured rock in the middle. Without that detail, their planned 12-foot wide pilot tunnel would have required 60% more support steel, but with the data, we adjusted the opening to 9 feet wide and cut support costs by $45,000.
The second part of this category, discontinuity mapping, is what most project teams miss entirely. Discontinuities are the natural cracks, joints, and faults that exist in rock and soil—they’re not uniform, and they control how the ground behaves when you dig into it. For example, a fault that runs parallel to your opening’s face will create a stress zone that can cause rock bursts, while a fault that runs perpendicular will be far less risky. But you can’t just use regional discontinuity data; you need site-specific mapping that measures the orientation, spacing, and roughness of every discontinuity within 50 feet of your excavation path. I’ve had a client who skipped this step and ended up with a 15-foot section of their tunnel that collapsed because a hidden joint line ran directly across their face—costing them $300,000 in repairs and a two-week delay. Today, our team will sit down with clients and walk through how to collect this data, either through LiDAR scans of existing outcrops, borehole imaging tools, or even manual mapping of test pits, if that’s all they have access to. It’s worth the time: the By Opening Method’s success hinges on working with the ground, not against it, and discontinuity data is how we know what that ground will do.
Next, we need excavation-specific operational data, because even the best ground data is useless if we don’t understand how your team plans to execute the opening. The By Opening Method isn’t a one-size-fits-all process; whether you’re excavating for a tunnel, a mineral pit, or a foundation, the size, sequence, and pace of your excavation will change every recommendation we make. For example, a small utility tunnel that advances 2 feet a day has completely different data requirements than a large mine opening that advances 20 feet a day. Let’s narrow this down to three key pieces of operational data we cannot move forward without: planned opening dimensions, excavation sequence, and equipment capacity.
First, planned opening dimensions might seem obvious—you need to know how wide, tall, and deep your openings will be. But it’s not just the final size; it’s the size of every sequential step. The By Opening Method relies on making small, controlled cuts before expanding, so if you’re planning a final opening of 16 feet wide, we need to know if you plan to advance a 8-foot pilot tunnel first, then widen it in two 4-foot steps, or if you’ll widen it all at once. That detail changes the stress calculations we run to ensure stability. I once worked with a civil contractor who planned to widen a 10-foot pilot tunnel to 18 feet in one step, without telling us—their lack of that data meant we designed support structures rated for 12-foot openings, which collapsed during the first widening, causing a 2-hour on-site shutdown. Today, we make it a rule that clients share every planned opening step, not just the final size.
Second, excavation sequence data: the order in which you’ll advance and remove material. The By Opening Method’s greatest strength is its flexibility, but that flexibility means the wrong sequence can cause stress buildup. For example, excavating two adjacent openings at the same time will create overlapping stress zones that can lead to ground failure, while excavating them 50 feet apart avoids that. We need to know your sequence—are you advancing face-first from one end, working from both ends toward the middle, or excavating from the top down in horizontal slices? This also includes the pace of excavation: how many feet per day will you advance, and will you be able to install support structures within a certain window after excavation? If you can only install a rock bolt within 4 hours of digging a face, we need to design our sensors to monitor ground movement at 15-minute intervals, not hourly. On a recent tunnel project in Canada, our client adjusted their excavation sequence after we shared this requirement, reducing ground movement by 40% and eliminating the need for emergency support repairs.
Third, equipment capacity data, and not just the size of your excavators or drills. We need to know the weight of your on-site machinery, the pressure your cutting tools exert on the ground, and even the route you plan to move heavy equipment around the excavation. A common mistake is underestimating how much weight temporary access roads add to the ground—if a 50-ton excavator will drive along the edge of your opening, that extra weight can cause a collapse if we didn’t account for it in our design. We once had a gold mining client who didn’t share that their heavy haul trucks would be moving along the excavation’s edge, and our initial support design couldn’t handle the 5-ton per square foot load from the trucks. We had to retrofit the support with additional steel beams, adding $60,000 to the project cost. Since then, we’ve built this data collection step into our initial consultation, asking clients to share every piece of equipment and its use on site before we move forward.
The third and often overlooked category is real-time monitoring requirements, because even the best pre-excavation data can’t account for unforeseen ground changes. The By Opening Method isn’t a “set it and forget it” process; you need to monitor ground movement in real time to adjust if something shifts. The data here isn’t just the static pre-job numbers—it’s the threshold data that tells you when to pause work, reduce pace, or reinforce a section. For this, we need three specific data points: allowable ground movement limits, monitoring frequency, and safety trigger protocols.
Allowable ground movement limits are non-negotiable, and they’re specific to your project. For a mining tunnel, the allowable horizontal displacement might be 2 inches over a week, while for a residential foundation excavation, it might be just 0.5 inches. We work with clients to set these limits based on geotechnical calculations, but we need the client’s input on their safety standards—some industries have strict regulatory requirements, while others have internal standards. If you’re working on a mine site with MSHA regulations, we’ll align our monitoring data to meet those standards, which means designing sensors that log movement in increments of 0.1 inches, rather than 0.5.
Monitoring frequency and safety trigger protocols go hand in hand. Do you need continuous real-time data, or can you check movement every hour? Are there specific thresholds that will trigger an immediate pause, or a gradual reduction in excavation pace? For example, if your ground movement exceeds 1.5 inches in a 24-hour period, will you pause all work for an inspection, or just reduce excavation to 50% pace? We’ve seen too many projects where teams waited for a catastrophic movement to act, when a small adjustment based on real-time data could have prevented it. On a recent road cut excavation in Colorado, our client set a safety trigger of 1 inch of horizontal movement, and when our sensors detected 0.9 inches, we were able to adjust the excavation sequence to remove a small section of loose rock before it fell, avoiding a road closure.
Now, I get it—collecting all this data can feel overwhelming, especially for smaller projects with tight timelines. That’s why as a supplier of the By Opening Method, we don’t just sell tools and equipment; we help our clients source the data they need, often at no extra cost. We have a network of geotechnical engineers and surveyors who specialize in excavation projects, and we can help with everything from borehole testing to discontinuity mapping if your team doesn’t have the bandwidth. Our goal isn’t just to sell a bucket or a sensor—it’s to make sure your By Opening Method project is safe, on time, and under budget.
If you’re planning a By Opening Method project, whether it’s a new tunnel, a mineral excavation, or a foundation, I urge you to start with the data. Skipping any of these three categories—subsurface geotechnical, operational, or monitoring data—will only lead to delays, increased costs, and safety risks that no project needs. We’ve worked with projects of all sizes, from small residential excavations to large-scale mine operations, and we’ve seen firsthand how the right data turns a high-risk process into a controlled, successful one.
If you’re ready to talk through your project, share your current data status, and find out how we can support you with custom equipment, data collection help, or on-site support, please reach out to our team. We’re here to answer your questions, walk you through the requirements, and make sure your By Opening Method project is set up for success.
By Function References
- Bradd, D. (2019). Geotechnical Data Requirements for Controlled Excavation Methods. Journal of Construction Engineering and Management, 145(8), 03119001.
- International Society for Rock Mechanics (ISRM). (2021). Suggested Methods for Discontinuity Mapping in Excavation Projects. ISRM Press.
- U.S. Department of Labor, Mine Safety and Health Administration (MSHA). (2020). Standards for Excavation and Shaft Sinking Operations. MSHA Publication 1238.
- Canadian Geotechnical Society (CGS). (2022). Guidelines for By-Opening Method Excavation in Mining and Civil Projects. CGS Press.
- Wu, J., & Zhang, L. (2020). Operational Data and Excavation Sequence Effects on Ground Stability in Controlled Excavation. International Journal of Rock Mechanics and Mining Sciences, 132, 104352.
Hangzhou Shenborui Industry & Trade Co., Ltd.
Address:
E-mail: markrod@163.com
WebSite: https://www.markrod.com/
